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Liver Injury Due to Drugs and Herbal Agents
24 Liver Injury Due to Drugs and Herbal Agents David E. Kleiner, md, phd
Brief Historical Overview 311 Incidence and Demographics 312 Clinical Manifestations 313 Microscopic Pathology 315 Necroinflammatory Patterns 315 Cholestatic Patterns 336 Steatotic Patterns 340 Vascular Injury Patterns 342 Pigments and Other Cytoplasmic Changes 342 Neoplasms 343 Grading and Staging 343 Differential Diagnosis 344 Determining causality 345 Ancillary Diagnostic Studies 349 Genetics 349 Treatment and Prognosis 349
Abbreviations ALT alanine aminotransferase AST aspartate aminotransferase CDER Center for Drug Evaluation and Research CDS clinical diagnostic scale CIOMS Council for International Organizations of Medical Sciences DILIN Drug-Induced Liver Injury Network FDA Food and Drug Administration HLA human leukocyte antigen NAFLD nonalcoholic fatty liver disease NAT2 N-acetyltransferase-2 NIDDK National Institute of Diabetes and Digestive and Kidney Diseases NRH nodular regenerative hyperplasia PAS periodic acid–Schiff PBC primary biliary cirrhosis PSC primary sclerosing cholangitis
RUCAM ULN UNOS VOD/SOS
Roussel Uclaf Causality Assessment Method upper limit of normal United Network of Organ Sharing veno-occlusive disease/sinusoidal obstruction syndrome
Brief Historical Overview
In 1965, Hans Popper and his coworkers1 published a landmark paper entitled “Drug-Induced Liver Disease: A Penalty for Progress.” He reviewed 155 cases of apparent liver toxicity, related to 30 different agents. He recognized that the information on the clinical and pathologic characteristics of drug- and toxin-induced injury was poorly organized and would benefit from a systematic attempt at classification. He therefore proposed dividing the pathologic changes into six basic categories: zonal injury, uncomplicated cholestasis, nonspecific drug-induced hepatitis with or without cholestasis, reactions simulating viral hepatitis, nonspecific reactive hepatitis, and drug-induced steatosis. To a large extent, the classifications used today are intellectual children of Popper’s classification, reorganized and expanded. The major additions include the spectrum of drug-induced vascular injury, mainly a product of chemotherapy and certain natural products; subcategories of cholestatic liver disease related to primary or secondary destruction of the ducts; and the category of drug-induced hepatic neoplasms. Identification of the pattern of injury under the microscope is the first job of the pathologist, because the pattern of injury determines the pathologic differential diagnosis and helps determine the mechanism of injury. A significant barrier to gaining a comprehensive understanding of drug-induced liver injury is the medical literature itself. The primary literature of human drug-induced liver injury is mainly in the form of case reports and small series scattered across the full breadth of the medical literature. There is huge variation in the quality of individual articles both in terms of the data being presented (including descriptions of pathologic changes) and the extent to which other causes of liver injury are excluded. In addition, because of advances in hepatology during the past 40 years, we are now better able to diagnose a number of conditions that could be mistaken for drug injury. For example, prior to 1988, chronic hepatitis C may have been present and been mistaken for chronic drug-induced injury (a factor to consider in reading 311
Practical Hepatic Pathology older literature). Beyond the primary literature are a host of review articles, some of which are highlighted at the end of the chapter. These can be helpful, but most are written from a clinical point of view and are published in a wide range of clinical subspecialty journals. There are also a number of recent monographs devoted to drug- and toxininduced liver injury, and although these are also written from a clinical point of view, they can offer significant insight into the pathology of drug-induced liver injury.2–6 In recognition of the need to bring structure to what is essentially an anecdotal science, there have been a number of efforts in the past several decades to scientifically evaluate drug-induced liver injury in humans. Beginning in 1985, the European pharmaceutical company Roussel Uclaf organized a series of consensus meetings in France on adverse drug effects. These meetings considered fundamental questions of injury classification and causality. These efforts culminated in 1993 with the publication of the Roussel Uclaf Causality Assessment Method (RUCAM), which is a numerical scoring system designed to help clinicians assign a degree of certainty to whether a particular agent is responsible for a particular case of hepatotoxicity.7 This system is further considered below. In the United States, the Food and Drug Administration (FDA) Center for Drug Evaluation and Research (CDER) has organized a number of meetings since 2001 involving the FDA, academia, and the pharmaceutical industry, which discuss various aspects of drug-induced liver injury. Documents relating to these meetings are freely available on the FDA’s website (www.fda.gov/Drugs/ScienceResearch/ResearchAreas/ ucm071471.htm). Another recent development has been the establishment of regional and multicenter clinical networks devoted to gathering cases of drug-induced liver injury. Networks exist in France8 and Spain,9,10 in the United States, as well as in other countries. In the United States, the Acute Liver Failure Study Group (acsresearch.swmed.edu/ ALF/home.html) prospectively collects cases of acute liver failure, a significant percentage of which are due to drug-induced liver injury.11,12 The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsored a U.S.-based Drug-Induced Liver Injury Network (DILIN; https://dilin.dcri.duke.edu/) that is actively accruing and characterizing cases of drug injury.13 Given the relatively low incidence of drug-induced liver injury (discussed later), one may justifiably wonder why it is so important to correctly identify and classify cases. One of the main reasons is that the subtle clinical presentation coupled with a potentially fatal outcome is of great concern to physicians and patients alike. Confirmed hepatotoxicity sometimes leads to regulatory action. Table 24-1 shows the drugs that have been either been removed from the U.S. market or flagged by black box warnings by the FDA for liver injury. A review of FDA regulatory actions over a 25-year period showed that liver injury was the most common reason for a drug to be withdrawn or have its use curtailed.14 Furthermore, every year, reports of first instances of hepatotoxicity of new drugs appear (Box 24-1), reinforcing the fact that we are unable to screen completely for potential hepatotoxicity in preclinical or clinical trial settings. Correct causal association of a drug with an injury coupled with properly reporting the injury is an important part of protecting patients and can lead to removing potentially harmful medications from the pharmaceutical armamentarium.
Incidence and Demographics It is difficult to assess the true incidence of drug-induced liver injury accurately for any particular agent. To know the incidence, one must have some information about the exposed population as well as some method of identifying all of the cases of injury. Both of these are subject to bias in data collection. Nevertheless, some statements can be made. In large, population-based studies, the overall incidence of drug-induced liver 312
Table 24-1. Hepatotoxicity Resulting in Food and Drug Administration Regulatory Actions Drugs Withdrawn
Black Box Warnings
Safety Alerts
Benoxaprofen
Dacarbazine
Acetaminophen
Bromfenac
Danazol
Leflunomide
Ticrynafen
Felbamate
Nefazodone
Troglitazone
Ketoconazole
Nevirapine
Pemoline
Pyrazinamide/rifampin
Tolcapone
Telithromycin
Trovafloxacin
Terbinafine
Valproate
Zafirlukast
Zalcitabine Zidovudine
Dietary supplements Kava Lipo KinetiX
Data from Lasser KE, Allen PD, Woolhandler SJ, et al: Timing of new black box warnings and withdrawals for prescription medications. JAMA. 2002;287:2215–2220; Watkins PB: Idiosyncratic liver injury: challenges and approaches. Toxicol Pathol. 2005;33:1–5; and Norris W, Paredes AH, Lewis JH: Drug-induced liver injury in 2007. Curr Opin Gastroenterol. 2008;24:287–297.
injury varies from about 2 to 150 per million person-years, depending on the population studied (Table 24-2). Drug classes frequently associated with hepatotoxicity include the antibacterials, particularly amoxicillinclavulanate and the sulfonamides; the antimycobacterials; nonsteroidal anti-inflammatory drugs; and antiseizure medications. In Singapore, herbal agents in the form of traditional Chinese medicines make up a significant proportion of cases.29,30 The prevalence of injury related to particular agents changes with time—Friis and colleagues examined 1100 adverse drug reactions reported to the Danish surveillance system from 1978 to 1987. During this time, the number of reactions due to halothane decreased, probably because of the reduced use of that anesthetic.31 Herbal usage by persons in the United States has risen progressively over the past 50 years,32 and although it is difficult to track the incidence of herbal-related liver injury, it is likely that cases will continue to rise in proportion to increased use. Liver injury accounts for a disproportionate amount of drug-associated mortality. In the Danish study, liver injury accounts for 5.9% of the adverse drug reactions but 14.7% of the deaths. Another study from New Zealand recorded similar findings. Surveys of acute liver failure (Table 24-3) show that druginduced liver injury usually accounts for a significant proportion of cases, from 15% of cases from the United Network of Organ Sharing Box 24-1. Drugs with Newly Reported Hepatotoxicity, 2005–2007 2008 Sorafenib15 Trastuzumab16 2007 Erlotinib17,18 2006 Anastrozole19 Atomoxetine20 Ezetimibe21 Telithromycin22 2005 Alosetron23 Bortezomib24
Liver Injury Due to Drugs and Herbal Agents Table 24-2. Estimates of the Incidence of Drug-Induced Liver Injury (DILI) Country
Years
Method of Case Accrual
Total Cases
Top Drugs Identified
Estimated Incidence of DILI (per million person-years)
United States25
1977–1981
HMO database
9
Ampicillin
2–4 for patients <40 years 20–80 for patients >60 years
Spain10
1993–1998
Referral
107
Acetaminophen, aspirin, ranitidine
7.4 (acute serious toxicity)
France8
1997–2000
Population-based
34
Augmentin, nevirapine, atorvastatin
140 (crude rate) 80 (standardized rate)
England26
1994–1999
Practice database
128
Acetaminophen, diclofenac, flucloxacillin
24 (with sixfold increased risk if two or more drugs suspected)
Spain9
1994–2005
Referral
461
Amoxicillin-clavulanate, ebrotidine, antimycobacterials
17 (severe toxicity) 34 (overall toxicity)
Sweden27
1995–2005
Practice database
77
Diclofenac, flucloxacillin, azathioprine
23
England28
1998–2004
Referral for jaundice
28
Amoxicillin-clavulanate, flucloxacillin
13 for jaundice-related DILI
24
HMO, health maintenance organization.
(UNOS) database36 to just over 50% of cases reported to the Acute Liver Failure Study Group.11 The proportion of drug-induced liver failure due to acetaminophen also varies considerably, from no cases in a Japanese cohort35 to 75% of cases in several U.S. and Canadian studies.11,38,41 Besides acetaminophen, other drugs that commonly top the lists include isoniazid, valproic acid, and halothane. Like incidence information, it is difficult to assess the demographic factors that are associated with drug-induced liver injury. Overall, the number of reports of drug-induced liver injury appear to increase with age,25,31 but whether this is due to true susceptibility or increased drug usage is not clear. In terms of specific drugs, children are more likely to be injured by aspirin42 and valproic acid43 and less likely to be injured by isoniazid,44 halothane,45 and erythromycin.46 For many drugs, there
is either insufficient information on age-related incidence or no apparent age effect. With respect to gender, studies show either more reports of liver-related drug injury in women31,33 or similar numbers between men and women.9 Women are much more likely to develop drug-associated autoimmune hepatitis than men, just as in idiopathic autoimmune hepatitis.47
Clinical Manifestations Hepatotoxic agents are classified clinically in several ways, but a common categorization is to divide them into intrinsic and idiosyncratic hepatotoxins (Table 24-4).48 Intrinsic hepatotoxins cause injury in a dose-dependent, reproducible manner that is usually testable in animal
Table 24-3. Drug-Induced Liver Injury (DILI) from Surveys of Acute Liver Failure Years
Method of Accrual
Fraction due to DILI (%)
Total Cases of DILI
Percent Acetaminophen Other Top Drugs
1991–1999
Hospital database
27
22
55
United States
1998–2001
Referral
52
160
75
Japan
1970–1998
Referral
95
0
Ecarazine, halothane
United States
1990–2002
UNOS database
270
46
Isoniazid, propylthiouracil, phenytoin, valproate
Sweden37
1966–2002
Adverse drug reports
103
14
Halothane, flucloxacillin, trimethoprim-sulfamethoxazole
United States, United Kingdom, Canada38
1999–2004
Pediatric referral
65
74
Valproate, isoniazid
WHO 39
1968–2003
Adverse drug reports
4690
6.5
Troglitazone, valproate, stavudine
Portugal40
1992–2006
Referral
23
14
0
Antimycobacterials, sulfasalazine, nimesulide
United States41
2000–2004
Population-based survey
54
35
77
Country Canada34 11
35 36
15
19
Isoniazid
UNOS, United Network of Organ Sharing; WHO, World Health Organization.
313
Practical Hepatic Pathology Table 24-4. Classification of Drug-Induced Liver Injury by Toxicity Category Category and Subcategory
Mechanism(s)
Intrinsic Direct Indirect
Idiosyncratic Immunologic
Metabolic
Toxin or metabolite reacts with multiple targets, resulting in massive disruption Drug metabolite disrupts specific metabolic pathway or selectively affects particular macromolecules
Other Features
Examples
Dose-dependent, can be reproduced experimentally Results in cell necrosis with usually little inflammation Effect depends on targets but usually pauciinflammatory
Carbon tetrachloride (hepatocytes), Paraquat (cholangiocytes) Acetaminophen (necrosis, steatosis), contraceptive steroids (cholestasis)
Low incidence, dose-independent, difficult to reproduce Drug metabolite reacts with macromolecules to Systemic symptoms and signs (fever, rash, form hapten for B- and T-cell mediated immune eosinophilia, autoantibodies), prompt responses recurrence to rechallenge Susceptibility to injury increased by genetic or acquired Variable time to onset, absence of immunologic inability to detoxify or eliminate injurious metabolites signs
models. They are further subclassified as either direct, in which the agent itself is the poison, or indirect, in which the agent is metabolized reproducibly to a toxic substance. Examples of direct hepatotoxins include carbon tetrachloride, which causes zone 3 necrosis and steatosis, and the herbicide Paraquat, which damages bile duct epithelium. Acetaminophen is a typical example of an indirect intrinsic hepatotoxin. Under normal conditions, it is adequately metabolized and excreted by the liver, but with high doses, increased induction of cytochrome P450 2E1, or reduced stores of cellular glutathione, it is metabolized to the active metabolite N-acetyl-p-benzoquinone, which can damage the cell.49 Finally, toxicity is classified by the target of the agent, usually either the hepatocyte, resulting in hepatocyte necrosis (usually along zonal lines), or the cholangiocyte, resulting in duct destruction. The injury caused by idiosyncratic hepatotoxins is unpredictable, not dose-dependent, and of low incidence compared with the intrinsic hepatotoxins. Idiosyncratic hepatotoxins are subdivided by mechanism of action into metabolic and immunologic hepatotoxins. Immunologic hepatotoxins share some common characteristics, including a drug sensitization period of at least 1 to 5 weeks prior to presentation with prompt recurrence of injury with rechallenge. They lead to hepatic injury that resembles autoimmune hepatitis or cholangitis. Systemic symptoms of fever, rash, and peripheral eosinophilia may be seen, and liver biopsies are more likely to have eosinophils or granulomas.50 Metabolic hepatotoxins differ from the immunologic hepatotoxins in several important respects. There is a widely variable latent period prior to the development of jaundice, and rechallenge does not cause immediate recurrence of the injury. The systemic features of hypersensitivity are absent in metabolic idiosyncrasy. Mechanisms of metabolic hepatotoxicity include genetic variation in pathways that process and detoxify drugs, competition for metabolic pathways by other drugs, or induction of pathways that lead to more toxic metabolites.51 The clinical presentations of drug-induced liver injury are almost as varied as the pathology. Patients may present in fulminant hepatic failure, with painless jaundice that mimics obstruction, with signs and symptoms of portal hypertension, with a mass lesion, or with asymptomatic enzyme abnormalities. The onset may be sudden or insidious. Because most drug reactions fall into either the necroinflammatory or the cholestatic categories, the biochemical changes in transaminases, bilirubin, and alkaline phosphatase are used to categorize the injury into a limited number of categories. In general, injuries that present mainly with transaminase (either alanine aminotransferase [ALT] or aspartate 314
Halothane, chlorpromazine, nitrofurantoin, erythromycins, phenytoin Isoniazid, valproic acid, amiodarone
aminotransferase [AST]) elevations are categorized as hepatocellular, whereas injuries characterized by elevated alkaline phosphatase are categorized as cholestatic. Injuries in which both transaminases and alkaline phosphatase are elevated are classified as mixed. This classification has been codified by the Council for International Organizations of Medical Sciences (CIOMS) at meetings organized by Roussel Uclaf. It is based on the ratio of ALT to alkaline phosphatase after normalization to the upper limit of normal for each test (Table 24-5).7,52 For the purposes of biochemical classification, the ratio is obtained from the time of onset of the injury. The ratio may vary as the injury progresses. If the patient is jaundiced, then that feature is added to the biochemical categorization. Thus, hepatocellular jaundice is an injury in which the transaminases are the predominant enzyme abnormality and jaundice is present. It is important to note that jaundice may be a component of any biochemical presentation and does not imply cholestatic biochemistries. It is also a mistake to extrapolate the biochemical pattern to the histologic findings. There is, at best, only a rough correlation between the biochemical categorization and the histologic patterns of injury described subsequently.53 Patients with a biochemically hepatocellular injury can have essentially any pathologic pattern on biopsy, including acute intrahepatic cholestasis with minimal inflammation. Biochemically cholestatic injury may show an acute lobular hepatitis pattern without evidence of cholestasis on biopsy. Thus, pathologic diagnostic terms such as hepatitis should be applied only if tissue is obtained for pathology review.52 Biopsies may be done for any of several reasons during the evaluation of drug-induced liver injury. Box 24-2 outlines some of the information that should be routinely evaluated in a liver biopsy done for drug injury. It is unusual to see a biopsy under circumstances Table 24-5. Biochemical Classification of Drug-Induced Liver Injury* Injury Category
Minimum Abnormality
R Values
Hepatocellular
ALT/ULN ≥ 2
R≥5
Mixed
ALT/ULN ≥ 2
2
Cholestatic
AP/ULN ≥ 2
R≤2
R = (ALT/ULN) ÷ (AP/ULN). ALT, alanine aminotransferase; AP, alkaline phosphatase; R, ratio; ULN, upper limit of normal. *Drug-induced liver injury is categorized based on the following equation:
Liver Injury Due to Drugs and Herbal Agents Box 24-2. Information Available from Liver Biopsies in Drug-Induced Liver Injury
• Determination of the pattern of injury • Correlation of injury pattern with published literature of particular agent • Assessment of the degree of injury (necrosis, duct paucity, fibrosis) • Identification or exclusion of other competing etiologies of liver disease • Pattern of injury may suggest mechanism of toxicity
where the diagnosis of drug injury is absolutely clear on clinical grounds. The clinical situation is therefore likely to be complicated by competing causes of liver injury or a complex drug history. In such a situation, the pathologist can help by carefully defining the pattern of injury and the pathologic differential diagnosis. A biopsy may also be done to rule out significant ongoing injury so that a critical drug may be continued. It is important to document the severity of the injury so that these kinds of clinical decisions can be made. On occasion, a liver biopsy may be done to evaluate enzyme changes or jaundice in a situation where drug injury is not suspected. In this case, the pathologist can play a significant role in bringing possible drug injury into the clinical differential diagnosis and helping to exclude other causes of liver disease.
Microscopic Pathology The diagnosis of drug-induced liver disease can be one of the most challenging and frustrating aspects of hepatic pathology. Essentially every pattern of liver disease may be observed, including patterns that are mixed and difficult to classify. Nevertheless, having a systematic approach to evaluating the liver biopsy and coupling that with identification of the pattern(s) of injury is the most fruitful approach. Although drug and herbal hepatotoxicity can replicate almost any nontoxic injury, individual agents do not usually show every kind of injury. Furthermore, it is important to remember that certain kinds of injuries are more often associated with drugs or toxic agents than other etiologies of liver disease (Table 24-6). Drug-induced liver injury should always be in the differential diagnosis when evaluating a liver biopsy, particularly one that is done to evaluate an as yet undiagnosed liver injury. Being alert to the Table 24-6. Histologic Features that Should Prompt a Search for Drug Injury Feature
Associated Drug Injury Mechanism
Eosinophils (prominent)
Hypersensitivity reactions
Granulomas
Hypersensitivity reactions
Zonal necrosis
Susceptibility to injury based on zonal variation in enzymes such as the cytochrome P450 family
Massive (fulminant) necrosis
Severe end injury of many drugs that cause intrinsic or idiosyncratic hepatocellular injury
Microvesicular steatosis
Mitochondrial injury
Vascular injury
Toxic injury to endothelial cells (acute and chronic) is associated with the entire spectrum of vascular injuries.
Mixed patterns Cholestasis + hepatitis Steatosis + necrosis
Mixed patterns suggest multiple cellular targets, a common effect of drug injury. Cholestatic hepatitis is a common pattern of idiosyncratic toxins, whereas steatosis and necrosis are observed with indirect hepatotoxins such as acetaminophen.
possibility of a toxic injury even when one is not suspected clinically can help keep the pathologist’s mind free of biases when reviewing a case. Hepatotoxic agents may injure any of the cell types in the liver: hepatocytes, cholangiocytes, endothelial cells, and even Kupffer cells. The primary cell type injured determines how the toxicity is manifested, particularly endothelial and cholangiocyte injuries. Primary injury to hepatocyte can result in necrosis, steatosis, and cholestasis. Inflammation can result either by involvement of the immune system in idiosyncratic hypersensitivity reactions or secondarily through recruitment of immune cells to sites of injury. A basic pattern-based classification of drug-induced liver injury is presented in Table 24-7 and an index to injury patterns caused by individual agents is given in Table 24-8. Pathologic terms such as hepatitis, cirrhosis, hepatocellular necrosis, and cholestatic hepatitis should not be used to describe a drug injury in the absence of pathologic confirmation.
24
Necroinflammatory Patterns It is frequently the case that patients with hepatotoxicity come to clinical attention because of the results of a necroinflammatory injury. A glance at Table 24-8 reveals that necrosis and inflammation involving hepatocytes are probably the two most common outcomes of druginduced liver injury. There is a huge variation in the degree of necrosis and inflammation that may be seen with any particular drug injury, from coagulative necrosis (usually zonal) with little or no inflammation to mild spotty lobular inflammation with little cell death to fulminant hepatitis with marked inflammation and nonzonal necrosis to patterns that mimic chronic viral hepatitis. Patterns of inflammation can be subdivided into patterns that mimic acute hepatitis, with a lobular predominance of inflammation, patterns that mimic chronic hepatitis (with or without fibrosis) and other more specific patterns, such as granulomatous hepatitis or mononucleosislike sinusoidal infiltrate. These distinctions are useful when formulating a differential diagnosis or in deciding how to further work up the case. It is also important to remember that all of these patterns may have a clinically acute presentation. Acute hepatitis-like injury is dominated by foci of lobular inflammation and spotty necrosis. The degree of severity may vary from a few widely scattered foci or apoptotic hepatocytes to large areas of bridging and confluent necrosis (Figs. 24-1 to 24-5). There is usually portal inflammation and interface hepatitis, sometimes severe, but the majority of the injury is in the lobule. Duct injury may be present, but cholestasis is not observed in the pure acute hepatitic drug injury. Hepatocellular changes can include ballooning and steatosis. There may be evidence of regeneration with the appearance of mitotic figures, widened hepatocyte plates, and hepatocyte rosette formation. Confluent necrosis in zone 3 is not an uncommon finding and may be the result of the toxic injury or extrahepatic causes such as shock. As the injury becomes more severe and the areas of necrosis merge, fulminant hepatitis with massive necrosis may be the result. Trichrome stains can help distinguish between recent parenchymal loss with collapse and parenchymal extinction seen in advanced cirrhosis (see Fig. 24-1C). Unless the injury has been present for longer than clinically recognized (as in some cases of subacute toxic hepatitis) or the patient has some underlying chronic liver disease, it is rare to see more than periportal fibrosis in this pattern of drug-induced liver injury. If canalicular or hepatocellular cholestasis is present along with the acute hepatitislike pattern of injury, then the case is better classified as a mixed cholestatic and hepatocellular type (cholestatic hepatitis), which is discussed subsequently in the section on cholestatic patterns. (Text continued on page 332)
315
316 Table 24-7. Classification of Drug-Induced Liver Injury (DILI) by Pattern of Injury Pattern
Characteristic Features
ALT AST xULN*
AP xULN*
Non-DILI Differential Diagnosis
Drug Examples
Acute (lobular) hepatitis
Lobular-dominant inflammation with or without confluent or bridging necrosis; no cholestasis
++ to ++++
±
Acute viral or autoimmune hepatitis
Isoniazid, sulfonamides, halothane, drugs associated with autoimmune hepatitis
Zonal coagulative necrosis
Zone 3 or 1 coagulative necrosis, usually without significant inflammation
++ to ++++
±
Hypoxic-ischemic injury (zone 3), Herpes and adenovirus usually cause nonzonal necrosis
Acetaminophen (zone 3), carbon tetrachloride (zone 3), ferrous sulfate (zone 1)
Submassive to massive necrosis
Extensive panacinar necrosis, variable inflammation
+++ to ++++
±
Fulminant viral or autoimmune hepatitis
Isoniazid, nitrofurantoin, methyldopa, many others
Chronic (portal) hepatitis
Portal-dominant inflammation, interface hepatitis (also includes mononucleosis pattern), with or without portal-based fibrosis; no cholestasis
+ to +++
±
Chronic viral or autoimmune diseases, early PBC/PSC, mononucleosis-associated hepatitis
Nitrofurantoin, methyldopa, sulfonamides, phenytoin (monopattern), drugs associated with autoimmune hepatitis
Mononucleosis-like hepatitis
Sinusoidal beading
+ to ++++
Variable
Epstein-Barr virus–associated hepatitis
Phenytoin
Granulomatous hepatitis
Inflammation dominated by granulomas (usually non-necrotizing), portal or lobular
+
+ to ++
Sarcoidosis, PBC, fungal and mycobacterial, atypical bacterial infections
Phenytoin
Acute cholestasis (intrahepatic, canalicular)
Hepatocellular and/or canalicular cholestasis in zone 3, may show duct injury but little inflammation
+
+
Sepsis, acute large duct obstruction
Erythromycin, estrogens, androgens, diazepam, diphenylhydantoin
Chronic cholestasis (vanishing bile duct syndrome)
Duct sclerosis and loss, periportal cholate stasis, portal-based fibrosis, copper accumulation
+
+ to ++
PSC
Floxuridine (by hepatic artery infusion)
Chronic cholestasis (PBC-like cholangiodestructive)
Florid duct injury with duct loss, periportal cholate stasis, copper
+
+ to ++
PBC, autoimmune cholangitis, chronic large duct obstruction
Chlorpromazine, amoxicillin-clavulanate, tolbutamide
Mixed hepatocellular-cholestatic (cholestatic hepatitis, hepatocanalicular)
Acute hepatitis pattern plus zone 3 cholestasis, inflammation may be very severe with confluent necrosis
+ to +++
+ to ++
Acute viral hepatitis
Very common DILI pattern: antibiotics, isoniazid, nitrofurantoin, diclofenac
Steatosis, microvesicular
Predominantly microvesicular steatosis, inflammation variable
+ to ++
±
Alcohol, fatty liver of pregnancy
Valproic acid, tetracycline, azathioprine, didanosine, fialuridine
Steatosis, macrovesicular
Predominantly macrovesicular steatosis without significant portal or lobular inflammation, no cholestasis
± to +
± to +
Very common finding in general population, alcohol, obesity, diabetes
Methotrexate, tamoxifen, valproic acid, many organics
Steatohepatitis
Zone 3 ballooning injury, sinusoidal fibrosis, Mallory bodies, variable inflammation and steatosis
± to +
± to +
Common finding in general population, alcohol, obesity, diabetes
Amiodarone, perhexiline maleate, tamoxifen, methotrexate
Necroinflammatory
Cholestatic
Steatotic
Vascular Sinusoidal dilation/peliosis
Sinusoidal alterations with/ without mild lobular inflammation, sinusoidal fibrosis
± to +
+ to ++
Sinusoidal obstruction syndrome/ veno-occlusive disease/BuddChiari syndrome
Occlusion or loss of central veins, thrombosis, with or without central hemorrhage and necrosis
+ to ++
Variable
Hepatoportal sclerosis
Disappearance of portal veins
Nodular regenerative hyperplasia
Diffuse nodular transformation, with or without mild inflammation and sinusoidal fibrosis
Artifactual, acute congestion, bacillary angiomatosis, nearby mass lesions
Androgens, estrogens, glucocorticoids, thioguanine, azathioprine Chemotherapeutic agents, bone marrow transplant prep regimen, certain teas
Arteriohepatic dysplasia
Arsenicals
Variable
+
Collagen-vascular diseases, lymphoproliferative diseases (but perhaps because of DILI)
Azathioprine, thioguanine, mercaptopurine, steroids
Hepatocellular adenoma
Variable
Variable
Sporadic adenomas
Androgens, estrogens, danazol
Hepatocellular carcinoma
Variable
Variable
Sporadic hepatocellular carcinoma
Androgens, estrogens, danazol, Thorotrast
Cholangiocarcinoma
Variable
Variable
Sporadic cholangiocarcinoma
Androgens, Thorotrast, vinyl chloride
Angiosarcoma
Variable
Variable
Sporadic angiosarcoma
Androgens, Thorotrast, vinyl chloride
Type 1 diabetes
Corticosteroids
Neoplasms
Cytoplasmic Alterations and Pigments Glycogenosis
Diffuse hepatocyte swelling with very pale bluish-gray cytoplasm
+ to ++
Ground-glass change
Diffuse homogenization of cell cytoplasm due to induction of smooth endoplasmic reticulum
Cytoplasmic inclusions
Discrete periodic acid–Schiff-positive cytoplasmic inclusions
Gold pigment
Granular black pigment in Kupffer cells
Gold
Thorotrast pigment
Grayish-gold, refractile pigment in Kupffer cells
Thorotrast
Phenobarbital Alpha-1 antitrypsin deficiency
Cyanamid
ALT, alanine aminotransferase; AP, alkaline phosphatase; ASP, aspartate aminotransferase; PBC, primary biliary sclerosis; PSC, primary sclerosing cholangitis; ULN, upper limit of normal. *±: normal to mild elevation (<3 × ULN), + : mild elevation (3–10 × ULN); ++: moderate elevation (10–20 × ULN); +++: marked elevation (20–100 × ULN); ++++: very marked elevation (>100 × ULN). Adapted in part from Zimmerman HJ (eds): Hepatotoxicity: The Adverse Effects of Drugs and Other Chemicals on the Liver. Philadelphia: Lippincott Williams & Wilkins; 1999.
24
317
318 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
PSC-like
End-Stage
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
Drug X
Acarbose Acetaminophen
X
X X
X
Acetohexamide Acetylsalicylic acid (aspirin)
X
Acitretin
X
X
X
X
X
X
X
X
X X
X
X
X
X
X X X X
Ajmaline X
Allopurinol
X
X
X X
Amineptine
X
X
X
X
X
X
X
X
Aminoglutethimide Amiodarone
X
Amitriptyline
X
Amlodipine
X X
X X
X
X
X
X
X
X
X
X
X
X
X X
Amoxicillin-clavulanate
X
X
X
X
X
Ampicillin
X
X
X
Ampicillin-sulbactam X
Amsacrine X
X X
X
X
X
X
X
X
X
X
X
Androgens Aprindine
X
‡
Adriamycin
Anastrozole
X
X
Actinomycin D
Amodiaquine
X
X X
X
X
X
X
X
X
X X
X
X
X
Asparaginase
X X
Atenolol X
Atomoxetine Atorvastatin
X
X
X
X
X X X X
Azacytidine X
Azapropazone
X
X
X X
Azathioprine
X
X
X
X
X X
X
X
X X
Benoxaprofen
X
Benzarone
X
Bromfenac
X
X
Bupropion
X
X
X
X X
X X
X
Busulfan
X
‡
Calcium hopantenate
X
Camphor
X
X
X
X
Candesartan Captopril
X
Carbamazepine
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Carbarsone
X
X
X X
Carbimazole
X X
Carboplatin Carbutamide
X
X
Bacille Calmette-Guérin (BCG)
Carbenicillin
X
X
Azithromycin
Benorylate
X
X
X
X
X X
Carmustine (BCNU)
X
X X
X
Cefadroxil
X
X
Cefazolin
X
X
X
Celecoxib
Cephalexin Chlorambucil
X
X
X
X
X X
X
Table continues on following page.
24
319
320 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
Chloroform
X
X
X
X
Chlorpropamide
X
Cimetidine
X
Cinchophen
X
X
X
X
X
X
X
X
X
X
X X
X
X X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X X
Cholestatic X
X X
X
Mixed
Hepatocellular
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
X
X
Cinnarizine
X X
X X
X
X
‡
X
Citalopram Clarithromycin
X
Clometacin
X
X X
X
X
X
Clopidogrel
X
Clorazepate
X
Corticosteroids
X X
X
X
X X
X
Chlorothiazide
Clozapine
Biochemical†
X
X
Chlorpromazine
Cloxacillin
Tumors
X
Chlorozotocin
Cisplatin
Vascular Injury
X
Chlorotetracycline
Ciprofloxacin
Steatosis
X
Chloropurine
Chlorzoxazone
PSC-like
X
End-Stage
PBC-like
X
Chronic Cholestasis (VBDS)
Chlordiazepoxide
Granulomas
X
Portal Hepatitis
X
Lobular Hepatitis
Chloramphenicol
Zonal Necrosis
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Necroinflammatory
X
X X
X
X X
X
X X
X
X
X
X X
X
Cromolyn
X
X
X
Cyamemazine
X X
Cyanamide X
Cyclofenil
X
X
X
X X
Cyclophosphamide X
Cyclosporin
X
X
X
Cytarabine
X X X
Dantrolene
X
Dapsone
X
X
X X
X X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X X
Daunorubicin
X
X
X
X
Demeclocycline
X
X
X
X
X
X X
Detajmium tartrate
X
X
X
X
X
X
Dextropropoxyphene Diazepam
X
Dichloromethotrexate
X
Diclofenac
X
X
X
X
X X
X
X
X
X
Dicloxacillin
X
Dicoumarol X
Didanosine
X
X
Dihydralazine
X
X
X
X
X X
Diflunisal
X X
Diethylstilbestrol
Dimethylbusulfan
X
‡
Desflurane
X
X X
Dacarbazine
X X
Cysteamine
Diltiazem
X
X
Cyproterone
Desipramine
X
X
Cyproheptadine
Danazol
X
X X
X
X
X
X
X
X X
Table continues on following page.
24
321
322 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
Duloxetine
X
Ebrotidine
X
X
X
X X
X X
X X
X
X
X
X
X
X
X X
Ethacrynic acid
X
X
X
X
X
X X
X
X
Ethambutol X
X X
X
Etodolac
X
X
Etoposide (VP-16)
X
X
Etretinate
X
X
X
X
Ezetimibe
X
X X
X
Fenofibrate
X
X
X X
X
X
Feprazone
X X
Felbamate
X
X
X
§
X
Fialuridine Floxacillin
Cholestatic
Hepatocellular X
X
Estrogens, synthetic
Ferrous sulphate
X
X
X
Erythromycin
X X
X X
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
Tumors
X
Erlotinib
Ethionamide
Vascular Injury
X
X
Enalapril Enflurane
Steatosis
X X
Doxidan
PSC-like
X
PBC-like
X
Chronic Cholestasis (VBDS)
X
End-Stage
Mixed
X
Mixed Cholestatic Hepatitis
Disulfiram
Acute Cholestasis
X
Cholestatic
Granulomas
Disopyramide
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X
X
X X
X
X
X
Floxuridine
X
X X
Fluconazole
X X
Fluoxymesterone
X
Fluphenazine
X
Flurazepam
X X
X
X
X X
X X
X
X
X
X X
Gemtuzumab
X
Gliclazide
X
Glyburide (glibenclamide)
X
X
Gold
X
X
X
X
X
Gemcitabine
X X
X
X
X
X X X
X
X
X
X
X
X
Griseofulvin Haloperidol Halothane
X
Hycanthone
X
X
X
X
X
X X
X
X X
X
X X
X
Hydrochlorothiazide
X
X
X
X
X
X
X
X
X
Hydroxyprogesterone
X
Hydroxyurea
X X
Ibufenac X
Ibuprofen
X
X
X X X
X
X
X
X
Idoxuridine Imatinib mesylate
X
Imipramine
X
X
X
X X
X X
Indicine X
Indinavir Indomethacin
X
X
Infliximab
X
X
X X
X
X X
X X
X
X
X
Hydralazine
Interferon alpha
X X
X
Flutamide Gatifloxacin
X
X
X
Fluoxetine
Fluroxene
X
X
X
X X
X
X X
X
X Table continues on following page.
24
323
324 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Interleukin-2
X
X
X
X
X X
Iodipamide meglumine
X
X
X X
Ipilimumab
X
X X
Iprindole
X X
Iproclozide X
X
X
X
X
Irbesartan
X
X
Isocarboxazid
X
X
Iproniazid
Isoflurane
X
Isoniazid
X
X X
X
X
X
X
X
X
X
X
X
X
Lamotrigine
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
Loratadine Losartan
X
X
Lergotrile
Lisinopril
X
X
X X
Labetalol
X
X
Ketoprofen
Levofloxacin
X
X
Itraconazole Ketoconazole
Cholestatic
X
X
Interleukin-6
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Steatosis
X
Interferon beta
Iodoform
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X X X X
X
Lovastatin
X
X
X X
Loxapine
X
X
Medroxyprogesterone
X X
Mefloquine X
Meglumine antimonate X
Mercaptopurine Mesalamine (mesalazine)
X
§
X
X X
Metformin
X
X
X
X
X
Methotrexate
X
X
X
X
X
X
X X
X
X
X
X
X X
X
X
X
X
X
Methylthiouracil
X
X
X X
X
X
X
X
X
Mirtazapine
X
X
X X
X
Monomethylformamide
X
X
Naproxen
X
X
X
X
Mitomycin C
Nevirapine
X
X
X
X
X
X X
Nefazodone
X
X
X
Minocycline
Niacin
X
X X
X
Mithramycin
X
X
X
Methyltestosterone
Metoprolol
X
X
Methyl salicylate Methyldopa
X
X
X
Methimazole
X
X X
Methandrostenolone
X
X
X
Mestranol
Methoxyflurane
X
X
X
X
X
X
X
X
X
X
Nimesulide
X
X
Nitrofurantoin
X
X
X
Nomifensine
X
Norethindrone
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
Nifedipine
X
X
X
X X
X
X
X
X
X X
Table continues on following page.
24
325
326 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
X
Granulomas
X
Portal Hepatitis
Lobular Hepatitis
Norfloxacin
Zonal Necrosis
Necroinflammatory
X
Novobiocin
X
X
Ofloxacin
X
X
X
X
X
Oxacillin
X
Oxaprozin
X
X
X
X
X
X
Oxymetholone
X
X
X
X
X
X
X
X X
Oxytetracycline Papaverine
X
X
X
X
X
X
X
X
X X
Penicillamine X
Penicillin
X
X
X
X
Pentamidine X
X
X
X
X
X
X
X
X
Phenazone Phenazopyridine
X
X
Paroxetine
Perhexiline maleate
X
X
X
Para-aminosalicylic acid
Pemoline
X
X
Oxyphenbutazone Oxyphenisatin
X
X X
Phenelzine Phenindione
X
Phenobarbital
X
Phenprocoumon
X
X
X
X X X
X
X
X
X
X
X
X
X
X X
Phenylbutazone
X
X
X
X
X
Phenytoin
X
X
X
X
X
Pioglitazone
X
X
Piroxicam
X
X
X
X X
X
X X
X
X
X
X X
Prajmalium
X
X
X
Pravastatin Probenecid
X
Procainamide
X
X
X X
X
X X
Prochlorperazine
X
X X
X
X
X
X
Propafenone X
Pyrazinamide
X
X
X
X
X X
X
X X
X
X
Quinethazone X
X
X
X
X
X
Quinine
X
Raloxifene X
Ramipril X
Ranitidine
X
X
X
X
X
X
X
X
Repaglinide X
X
X
X
X
X X
Rofecoxib X
Rosiglitazone X X
X
X
Sibutramine
X
X
X
X
X X
X
X
X
X X
Sevoflurane
X X
X
Ritonavir
Rosuvastatin
X
X
Risperidone
X X
X
Riluzole
Roxithromycin
X
X
Practolol
Rifampin
X
X
Pizotifen
Quinidine
X
X
Pirprofen
Propylthiouracil
X
X X X
Table continues on following page.
24
327
328 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Streptozotocin
X
Sulfadiazine
X
X
Sulfadoxine-pyrimethamine
X
Sulfamethizole
X
Sulfamethoxazole
X
Sulfasalazine
X
X
Sulindac
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X X X
X
X
X
X
X
X
X
X
X
X X
X
Tacrine
X
X
X X
Tamoxifen X
X
X
X X
Terbinafine Terfenadine
X
Testosterone
X
X
X
X
X
X X
X
X
X
X
X
X
X
X X
X X
Tetracycline X
X
X
X
X
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
PSC-like
X
Sulpiride
Thioguanine
Vascular Injury
X
Suloctidil
Thiabendazole
Steatosis
X
Sulfadimethoxine
Thalidomide
PBC-like
X
Streptokinase
Telithromycin
End-Stage
X
Stavudine
Tacrolimus
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
X
Cholestatic
Acute Cholestasis
X
Granulomas
Portal Hepatitis
Simvastatin
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X
X
X X
X
X
X
X
X X
X
X
X
X
X
Thiopental X
Thioridazine X
Thiotepa
X‡
Thorium dioxide (Thorotrast)
X
Ticarcillin-clavulanate
X
X
X
X
X X
X X
X
X
X
X
X
X
X
Tocainide
X
X
X
X
Tolbutamide
X
X
X
X
X
X
X X
X X
Tolcapone
X X
Tolmetin Toloxatone
X
X
Tiopronin
Tolazamide
X X
Ticlopidine Ticrynafen
X
X
X
Total parenteral nutrition
X
Tranylcypromine
X X
Trazodone
X
X
X
X
X X
X
X
X
X
Triazolam
X
X
Trichlormethiazide Trifluoperazine
X
Trimethobenzamide
X
X
Trimethoprim
X
X
X
Trimethoprim-sulfamethoxazole
X
X
X
X
X
X
Trovafloxacin
X
Urethane
X
Valproic acid
X
Venlafaxine
X
X
X
X
X X
X
X X X
X
X
X
X X
X
X X
X
X X
X
Troleandomycin
Verapamil
X
X
Tripelennamine Troglitazone
X
X
X
X
X
Table continues on following page.
24
329
330 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Vitamin A X
Warfarin
X
X X
X
X
X
X
X
Xenylamine X
Ximelagatran
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
X
Sinusoidal Dilation
Budd-Chiari
X‡
Peliosis
VOD/SOS
Vincristine
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X X
Zafirlukast
X X
Zidovudine
X
X
Zimelidine
X
Zoxazolamine
X
Herbal Agent X
Barakol Black cohosh
X
X
X
X X
Bush tea (pyrrolizidine alkaloids) X
Cascara sagrada Chaparral
X
X
X
X
X
Chaso/Onshido
X
X
X X
X
X
X
X
Green-lipped mussel (Seatone) Jin bu huan
X
X
Glycyrrhizin Greater celandine
X
X
Comfrey Germander (Teucrium)
X
X
X
X
X
X
Kava kava Ma huang
X
X
X
X X
Margosa oil
X
Mate tea X
Mineral oil Oil of cloves
X
Pennyroyal oil
X
X X X
Pentanoic acid X
Polyvinyl pyrrolidone
X
Prostata X
Senna X
Skullcap Syo-saiko-to
X
Tannic acid
X
Usnic acid
X
X
X
X X
X
NRH, nodular regenerative hyperplasia; PBC, primary biliary cirrhosis; PSC, primary sclerosing cholangitis; VBDS, vanishing bile duct syndrome; VOD/SOS, veno-occlusive disease/sinusoidal obstruction syndrome. *The patterns of pathology and biochemistry presented in this table are meant to be general guides and not absolute criteria. † Biochemical injury as defined by the ratio of alanine aminotransferase to alkaline phosphatase as described in the text. ‡ Only in combination with other agents or radiotherapy. § Predominantly zone 1 necrosis. Data were compiled from multiple sources, including the primary literature, as well as Zimmerman HJ (eds): Hepatotoxicity: The Adverse Effects of Drugs and Other Chemicals on the Liver. Philadelphia: Lippincott Williams & Wilkins; 1999; Norris W, Paredes AH, Lewis JH: Drug-induced liver injury in 2007. Curr Opin Gastroenterol. 2008;24:287–297; Snover DC: Drug-induced liver disease. In: Snover DC (ed): Biopsy Diagnosis of Liver Disease, Baltimore, MD: Williams & Wilkins; 1992, pp. 164–177; Lewis JH, Ahmed M, Shobassy A, et al: Drug-induced liver disease. Curr Opin Gastroenterol. 2006;22:223–233; Lazerow SK, Abdi MS, Lewis JH: Drug-induced liver disease 2004. Curr Opin Gastroenterol. 2005;21:283–292; and Arundel C, Lewis JH: Drug-induced liver disease in 2006. Curr Opin Gastroenterol. 2007;23:244–254.
24
331
Practical Hepatic Pathology
A
B Figure 24-1. Nitrofurantoin toxicity—acute fulminant hepatitis. Nitrofurantoin has been associated with both acute and chronic liver disease. The biochemical presentation varies from pure hepatocellular to cholestatic, and most of the reported cases are in women and in older individuals. Toxicity may not develop until the patient has been on the drug for several years, and yet the patient may still present in fulminant hepatic failure. The histopathology mainly shows changes of hepatitis and the distribution, and severity may mimic both acute and chronic viral hepatitis. Severe fibrosis and cirrhosis may be present at the time of biopsy. This patient presented with acute hepatitis and jaundice. (A) The biopsy shows lobular inflammation associated with ballooning injury of hepatocytes. There is extensive hepatocyte drop-out in zone 3 in this portion of the biopsy, whereas other areas show panacinar necrosis. (B) The infiltrate is mainly lymphocytic with scattered eosinophils and plasma cells. Hepatocellular rosettes are present. Canalicular cholestasis is not seen. (C) A Masson stain in an area of panacinar necrosis shows relatively preserved portal areas with collapse of intervening parenchyma. No hepatocytes remain in this portion of the biopsy, but there is a ductular reaction and persistent inflammation (Masson trichrome).
C
Drugs may also cause a pattern of injury that may be indistinguishable from chronic viral or autoimmune hepatitis on histologic grounds alone (Figs. 24-6 and 24-7). In fact, many of the drugs that can cause the acute or lobular hepatitis pattern may also cause one resembling chronic hepatitis. Some common agents associated with the chronic hepatitis-like pattern include nitrofurantoin, isoniazid, and the sulfonamides (see Table 24-8). In these biopsies, there is generally portaldominant inflammation with interface hepatitis associated with a mild to moderate degree of spotty lobular inflammation. Apoptotic hepatocytes as well as other evidence of injury such as ballooning degeneration and steatosis may be seen. As with the acute hepatitis-like injury, if canalicular or hepatocellular cholestasis is present, these cases should be classified with the mixed cholestatic and hepatocellular type for the purposes of differential diagnosis. This pattern of injury tends to have lower transaminase elevations than the acute hepatitis forms and may go undetected for a long time. Cirrhosis may develop, as in the case of nitrofurantoin toxicity shown in Figure 24-7. In such cases, other causes of cirrhosis should be excluded histologically and clinically. Drugs that cause chronic hepatitis patterns may be further subdivided by whether or not they are associated with features of autoimmune hepatitis.54 A number of drugs, including nitrofurantoin55 (see Figs. 24-1, 24-6, and 24-7), methyldopa,56,57 and minocycline,58 induce an autoimmune hepatitis that is clinically similar to sporadic type I autoimmune hepatitis and termed drug-induced chronic hepatitis, type 332
I. Patients frequently have circulating antinuclear and/or anti–smooth muscle antibodies, high gamma globulin levels, and plasma cell–rich infiltrates on liver biopsy. Like the sporadic form of autoimmune hepatitis, there is a female predominance, and the onset may be acute or chronic. A second group of drugs is associated with autoantibodies directed against microsomal proteins such as isoforms of cytochrome P450, similar to type II autoimmune hepatitis. These drugs are categorized as inducers of drug-induced chronic hepatitis type II and include dihydralazine (anti-CYP1A2),59 ticrynafen (anti-CYP2C9),60 and halo thane (anticarboxylesterase and anti–protein disulfide isomerase).61 A third group includes drugs such as sulfonamide, lisinopril, and trazodone that have not yet been associated with an autoantibody but may show chronic hepatitis-like histology. Phenytoin, dapsone, and several other agents have been associated with a pseudomononucleosis type of inflammatory pattern.62,63 There is sinusoidal beading present, and both phenytoin and dapsone may also induce granulomas and eosinophils. Infection by Epstein-Barr virus should be excluded by the usual means. A large number of drugs have been associated with granulomatous inflammation (see Table 24-8). The presence of microgranulomas (small collections of 3 to 10 epithelioid macrophages) in the hepatic parenchyma is a common finding in many types of chronic liver disease. They should not, by themselves, lead to a diagnosis of granulomatous h epatitis, drug-induced or otherwise. Larger epithelioid granulomas, particularly
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B Figure 24-3. Lamotrigine toxicity. Lamotrigine is an antiepileptic drug that has recently been associated with an acute hepatitic type of hepatotoxicity. (A) This biopsy from a patient with lamotrigine hepatitis shows several large foci of lobular inflammation associated with hepatocellular apoptosis. The inflammation is lymphohistiocytic with eosinophils. (B) The portal areas are filled by a lymphocytic infiltrate with numerous eosinophils. Interface hepatitis is present, and several apoptotic hepatocytes can be seen at the edges of the portal area. The ducts are relatively unaffected by the infiltrate. There was no cholestasis visible in the biopsy.
C Figure 24-2. Isoniazid hepatitis. Isoniazid causes hepatocellular injury with jaundice in about 1% of patients. The incidence increases with age and alcohol use. Patients on more than one antituberculous agent may also be at risk for hepatotoxicity. The histologic pattern of injury varies from acute hepatitis to cholestatic hepatitis. (A) This example of isoniazid injury shows diffuse lymphocytic inflammation involving portal areas and hepatic parenchyma with hepatocyte drop-out. Scattered eosinophils are present, but plasma cells are only rare. (B) At high magnification, acidophil bodies are readily identified. There is wide variation in hepatocyte cell size, consistent with regeneration. (C) In this case, there is mild duct injury. The ductal epithelial cells show reactive changes, with nuclear variation and crowding. There is also a prominent ductular reaction with a neutrophilic infiltrate. No canalicular or hepatocellular cholestasis is seen in this case despite significant jaundice.
Figure 24-4. Ciprofloxacin hepatitis. Ciprofloxacin has been associated with both hepatitic and cholestatic jaundice. In this case, there is both portal and lobular inflammation, with eosinophils and plasma cells in the infiltrate. There was no cholestasis in the biopsy. 333
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Figure 24-5. Herbal-associated hepatotoxicity. Hepatotoxicity due to herbal nutritional supplements has been the subject of a number of case reports and small case series. Pathology ranging from fulminant hepatitis to cholestasis to sinusoidal obstruction syndrome has been observed. (A) This biopsy was obtained from a patient with acute hepatitis due to a green tea extract. There is prominent necrosis in zone 3 associated with a predominantly lymphocytic infiltrate. There is bridging necrosis between the central vein and the adjacent portal area. (B) This biopsy was obtained during an episode of jaundice due to chaparral (beechwood creosote). There is a predominantly lobular hepatitis without cholestasis. The moderate steatosis present was most probably related to the patient’s obesity.
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Figure 24-6. Nitrofurantoin toxicity–chronic hepatitis pattern. This case presented with moderate elevations of transaminases and a normal bilirubin. (A) The distribution of inflammation observed at low power is mainly portal and periportal, mimicking chronic viral hepatitis. The lobular inflammation is relatively mild compared with the acute hepatitis presentation in Figure 24-1. (B) The portal areas show lymphoplasmacytic infiltrates with scattered eosinophils. There is interface hepatitis, and the duct is uninjured. (C) A feature not consistent with chronic viral hepatitis is the presence of central necrosis. Similar to the acute hepatitis presentation, there is accentuation of inflammation and necrosis in zone 3. (D) Focally, bridging necrosis is present, here connecting a central vein region with a portal area. This is another feature of severity that would be unusual in chronic viral hepatitis but would be more common in autoimmune hepatitis. 334
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C Figure 24-7. Advanced liver disease due to nitrofurantoin. Patients who develop nitrofurantoin toxicity may develop advanced fibrotic liver disease. This biopsy was taken about two months after the acute presentation at a time when the transaminases were only mildly elevated. (A) There is clear evidence of bridging fibrosis and nodule formation consistent with at least incomplete cirrhosis. Mild to moderate lymphocytic inflammation is present with focal interface hepatitis (Masson trichrome). (B) Some portal areas showed cholate stasis of the periportal hepatocytes, here associated with the absence of the bile duct. (C) Copper accumulation was seen in some of the periportal hepatocytes (rhodanine). The chronic cholestatic features in this case may be due as much to the advanced stage of the liver disease as to drug toxicity.
when present in significant numbers, may be a clue to drug-induced injury, particularly when sarcoidosis and infections have been excluded. In McMaster’s series of 95 cases of granulomatous hepatitis, about 30% were attributed to drugs.64 A wide variety of drugs were incriminated, including antihypertensives, anticonvulsants, antirheumatics, antimicrobials, antiarrhythmics, antineoplastics, anxiolytics, and contraceptives. Other authors have noted a lower incidence related to drugs, anywhere from 1% to 10%.65–68 The drugs for which granulomas are a common component of the injury include allopurinol, carbamazepine, copper sulfate, diphenylhydantoin, phenylbutazone, phenytoin, quinidine, and quinine.69 Granulomas in drug injury may be parenchymal, portal, or periductal, mimicking the florid duct lesion of primary biliary cirrhosis. Fibrin-ring granulomas have been associated with allopurinol.70 Eosinophils may be seen in and around drug-induced granulomas, and granulomas may be an indicator of hypersensitivity reactions. The death of hepatocytes usually takes one of two forms, apoptosis and necrosis.71,72 Apoptosis, or single cell death, is observed in most drug-induced injuries to some degree. Apoptotic hepatocytes are recognized as small, shrunken, hypereosinophic bodies with or without a condensed, fragmented nucleus. They may be found associated with clusters of inflammatory cells, adjacent to larger areas of necrosis or occasionally as free bodies in the sinusoids. In the context of druginduced injury, apoptosis may result from selective injury to organelles that triggers the death pathway or by initiation of apoptosis by immune cells during a hypersensitivity reaction. There is usually no clear zonal distribution of apoptosis in drug injury. Idiosyncratic drug injuries are most often associated with apoptotic cell death rather than necrosis. However, in severe cases of necroinflammatory drug injury, hepatocellular cell death may occur so rapidly and completely that it is no longer possible to distinguish the actual mechanism of cell death. In contrast to apoptosis, necrosis occurs when a cell receives massive injury in a short period of time. This injury can result from an environmental cause, such as sudden, severe hypoxia, thermal injury, or massive injury from a drug or toxin. Cell membranes and organelles are injured indiscriminately, and the cell rapidly loses all internal integrity. Because the lobular architecture of the liver defines a hepatocyte’s access to blood flow and oxygen as well as the levels of detoxifying enzymes, necrosis frequently occurs in a zonal distribution. Intrinsic hepatotoxins, both direct and indirect, are often incriminated when zonal necrosis is the dominant form of injury. Zonal necrosis usually involves either zone 3 or zone 1. Zone 2 necrosis has been produced in experimental model systems of toxicity but is very rare in human drug injury. Idiosyncratic toxins may also produce zonal injury, perhaps as a result of increased susceptibility of cells in particular zones or from particularly intense perivenular or periportal inflammatory infiltrates. Zone 3 necrosis is the most common form of zonal necrosis and is the characteristic form of toxicity due to acetaminophen and carbon tetrachloride. In the case of both of these agents, there is little inflammation except for macrophages and neutrophils that have been drawn to the area secondarily. Early on after the initiation of the injury, a biopsy will show sheets of hepatocyte ghosts in a zone 3 distribution (Fig. 24-8). Hemorrhage can be seen as the sinusoidal structure breaks down, and steatosis may be seen in the non-necrotic liver. The entire acinus may be involved in severe injuries. If the patient survives the initial toxic insult, the dead hepatocytes will be phagocytized and removed, leaving a zone of collapsed reticulin. With sufficient time, the liver can regenerate to the point where the architecture is essentially normal. Zone 1 coagulative necrosis is rarer but has been associated with poisoning by direct intrinsic hepatotoxins such as phosphorus,73,74 ferrous sulfate,75 and concentrated acetic acid.76 Finally, it should be remembered that zonal necrosis (particularly zone 3 necrosis) may be observed in hepatitic and vascular patterns of drug injury.
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Figure 24-8. Zonal necrosis due to acetaminophen. Acetaminophen causes a distinctive pattern of coagulative, zonal necrosis with minimal inflammation consistent with its intrinsic toxicity. The degree of toxicity increases with increased dose, increased acetaminophen blood levels, increased cytochrome CYP2E1 activity, decreased glutathione stores, increased alcohol consumption, fasting, and obesity. (A) There is coagulative necrosis of hepatocytes involving about 50% of the parenchyma. (B) At the interface between the viable and necrotic liver, there is steatosis and ballooning of hepatocytes. (C) In the viable areas of the liver, isolated apoptotic hepatocytes can be seen, along with mitotic figures. (D) In this biopsy from a case of acetaminophen toxicity in a chronic alcoholic, the lipid vacuoles in the steatotic hepatocytes fuse to form large irregular lipid lakes. (Courtesy of Dr. Linda Ferrell, University of California, San Francisco)
Cholestatic Patterns Cholestatic presentations of liver injury are not as common as hepatitic presentations, accounting for only 17% of cases in a large series from Denmark.31 Like the hepatitic patterns of drug-induced liver injury, the cholestatic patterns may be subdivided into several forms that mimic acute and chronic nondrug cholestatic liver disease. On the acute side are the patterns of pure intrahepatic cholestasis and mixed hepatocellular-cholestatic injury or cholestatic hepatitis (see Table 24-8). Acute intrahepatic cholestasis is characterized mainly by the accumulation of bile within canaliculi (canalicular cholestasis) and hepatocytes (hepatocellular cholestasis) (Figs. 24-9 to 24-11). Within hepatocytes, bile may be difficult to distinguish from other hepatocellular pigments such as lipofuscin and iron. Bile appears as variably sized rounded inclusions that are pale green to greenish brown in color. Iron stains can be very helpful by both excluding the possibility of iron and allowing the cytoplasmic pigments to be more clearly seen (see Fig. 24-9D). The low background counterstain used in rhodanine stains is also useful for visualizing intracellular bile (see Fig. 24-10C). Ballooning hepatocellular injury may accompany the bile stasis. Cholestasis is most prominent 336
in zone 3; other processes such as sepsis and acute large duct obstruction that may also present with isolated zone 3 cholestasis should also be excluded. In the most pure forms of acute intrahepatic cholestasis, such as the cholestasis from androgenic or contraceptive steroids, there is little or no inflammation. In most cases of drug-induced cholestasis, both hepatocellular and canalicular cholestasis are present, although the sex steroids notably produce only canalicular cholestasis. A mild degree of lobular and/or portal inflammation as well as duct injury may also be present. It is much rarer to see bile plugs in interlobular ducts or cholangioles in drug-induced cholestasis although benoxaprofen has been reported to cause both.5 As the degree of inflammation associated with the intrahepatic cholestasis increases, the cases are better classified as mixed hepatocellular-cholestatic injury (cholestatic hepatitis). The reason for making this distinction has more to do with the pathologic differential diagnosis than with distinctive patterns of drug injury, because many drugs that cause cholestatic hepatitis are also associated with blander forms of cholestasis or with the acute hepatitis pattern (see Tables 24-7 and 24-8). This mixed pattern of injury is a common pattern of drug-induced liver
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E Figure 24-9. Cholestatic injury due to amoxicillin-clavulanate. Patients who develop toxicity to amoxicillin-clavulanate usually present after they have completed their course of therapy. The injury is usually cholestatic and is recognized by the development of jaundice 1 to 9 weeks after stopping the drug. Histologically, all forms of cholestatic injury have been reported, from pure intrahepatic cholestasis to mixed hepatitic/cholestatic injury to vanishing bile duct syndrome. (A) Pure intrahepatic cholestasis injury shows little inflammation—usually a sparse portal infiltrate and very rare foci of spotty necrosis, leading to a nearly normal appearance at low magnification. (B) Careful examination reveals canalicular cholestasis (arrow), occasional enlarged hepatocytes with clearish, microvacuolated cytoplasm and small clusters of pigmented macrophages. (C) This biopsy from a case with mixed injury shows numerous foci of spotty lobular inflammation alongside canalicular and hepatocellular cholestasis. (D) Iron stains are helpful in distinguishing pigments in the liver. Bile plugs may be easier to see in an iron stain than in a standard hematoxylin and eosin because the brownish-green bile pigment contrasts well with the pale pink of the background in an iron stain. (E) Duct injury is frequently seen in cases of amoxicillin-clavulanate injury. In this case it took the form of primary biliary cirrhosis– like florid duct lesions. The ductal epithelium is extensively infiltrated and shows a hyperplastic response. There is a prominent eosinophilic infiltrate and cholate-stasis changes in the periportal hepatocytes. 337
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Figure 24-10. Azithromycin toxicity. Intrahepatic cholestasis and cholestatic hepatitis are typical patterns of injury with the macrolide antibiotics. Injury has been more often reported with erythromycin than with the other members of the drug family. This case demonstrated acute intrahepatic cholestasis with loss of the small bile ducts. (A) There is zone 3 cholestasis with accumulation of bile pigment mainly in hepatocytes, although canalicular cholestasis is also present. This accumulation is associated with mild hepatocyte swelling and occasional hepatocyte apoptosis. There is almost no inflammatory infiltrate. (B) Most of the small portal areas lacked a visible bile duct, but there was no evidence of periportal cholate-stasis. (C) The copper stain was negative for copper accumulation, but the zone 3 bile stasis was evident as a greenish discoloration (upper left) (rhodanine stain). 338
Figure 24-11. Cholestatic injury with duloxetine. Duloxetine has only recently been associated with hepatotoxicity with a reported case of fulminant hepatic failure. Here are two examples of cholestatic injury judged to be due to duloxetine. (A) The first case shows acute intrahepatic cholestasis with very little inflammation. There is no hepatocellular drop-out, but scattered pigmented macrophages are seen in the sinusoids. There is only mild portal inflammation without interface hepatitis. (B) Under high magnification, canalicular and hepatocellular cholestasis are identified, mainly around the central veins. (C) A separate case shows mixed hepatocellular and cholestatic injury, with lobular inflammation, hepatocyte drop-out and canalicular cholestasis. There is prominent Kupffer cell hypertrophy in the sinuses (pale cells between hepatocyte cords).
Liver Injury Due to Drugs and Herbal Agents injury, but it is unusual outside that context. Lewis and Zimmerman further divided this pattern into three: mixed-hepatocellular, mixed hepatocanalicular, and mixed cholestatic, depending on whether hepatitic or cholestatic features predominated.77 All cases show some degree of hepatocellular injury, with inflammation of the lobules and portal areas along with zone 3 predominant canalicular and hepatocellular cholestasis (Figs. 24-12 to 24-14; see Figs. 24-9 and 24-11). The inflammatory pattern may mimic either the acute or chronic hepatitis-like patterns described earlier, although it is more common to see the acute hepatitis pattern. Duct injury may be present, and with some drugs such as amoxicillin-clavulanate, chlorpromazine, and trimethoprim-sulfamethoxazole, patients may develop a vanishing bile duct syndrome.78–80 Drugs may cause a variety of injuries that can be grouped together under the general pattern of chronic cholestasis. These include patterns of ductal paucity, often termed vanishing bile duct syndrome, and injuries that mimic the more specific lesions of primary sclerosing cholangitis
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C B Figure 24-12. Fluvastatin-related cholestatic hepatitis. Statins are only very rarely causes of significant hepatic injury. Because statins are used in a patient population (hypercholesterolemics) that is at risk for fatty liver disease, these patients may have mildly elevated transaminase levels unrelated to drug therapy. This case of fluvastatin toxicity demonstrated mild mixed hepatocellular and cholestatic injury on biopsy. (A) Examination of zone 3 shows canalicular cholestasis associated with mild lobular inflammation and hepatocellular apoptosis. There was also mild duct injury. (B) A PAS stain performed with diastase digestion shows numerous small clusters of PAS-positive macrophages in zone 3.
Figure 24-13. Trimethoprim-sulfamethoxazole–related injury. The combination drug trimethoprim-sulfamethoxazole causes a wide range of injury from nearly pure intrahepatic cholestasis to acute hepatitis, with cholestatic presentations being more common. This case shows mixed hepatocellular and cholestatic injury on a background of mild fatty liver disease, probably related to obesity. (A) The inflammatory infiltrate is mild in intensity and present mainly in the portal areas. There is interface hepatitis as well as ductular reaction, both of which obscure the limiting plate. (B) The portal infiltrate is mainly lymphocytes, with increased numbers of eosinophils. (C) Canalicular cholestasis is present throughout the lobule but is most visible in zone 3. 339
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Figure 24-14. Atomoxetine toxicity. Atomoxetine is a recently developed norepinephrine reuptake inhibitor used to treat attention-deficit hyperactivity disorder. Several case reports have linked it with hepatotoxicity. This biopsy was obtained in the midst of the biochemically hepatitic presentation associated with jaundice. The histologic pattern of injury is a cholestatic hepatitis with the hepatitic component being the more prominent one. (A) At low magnification, there is both portal and lobular inflammation, with evidence of hepatocellular injury in the form of ballooning and hepatocyte rosette formation. (B) There is a mild to moderate portal inflammatory infiltrate with interface hepatitis and scattered eosinophils. This portal area had no visible duct, but ducts were present in most other portal tracts. (C) In zone 3 there is evidence of focal hepatocyte drop-out and dilated canaliculi with pale bile accumulation. (D) The canalicular cholestasis is more apparent on the iron stain, where it is seen as pale greenish-pink plugs in canaliculi.
(biliary sclerosis) and primary biliary cirrhosis.77,81 Drugs and other toxins may directly injure the cholangiocytes,82 or the ducts may be destroyed secondarily by inflammation or ischemia. Duct injury by itself should not be taken as the characteristic lesion of chronic cholestasis, because it may be observed in the hepatitic and cholestatic patterns discussed earlier. It is more important to evaluate all of the portal areas systematically and assess the status of the main duct—intact, injured, inflamed, or missing. Cytokeratin 19 stains may be useful in identifying duct remnants obscured by inflammation. Ductular reaction may be present with duct loss, but it is not a specific finding. It is better to look for evidence of cholate stasis (Fig. 24-15; see Fig. 24-9E), the microvacuolar change in periportal hepatocytes that is the result of bile salt accumulation. Copper stains can also be useful markers in the evaluation of chronic cholestasis, although they may also be positive in advanced stage liver disease from all causes. Fibrosis can develop secondarily as in other chronic cholestatic liver diseases. The primary sclerosing cholangitis–like injury of biliary sclerosis is a relatively unusual pattern of chronic cholestatic drug injury, associated mainly with hepatic arterial infusion of floxuridine83,84 as well as with the treatment of echinococcal 340
cysts with scolicides.85 The injury has been attributed to arterial damage by the agents rather than direct injury to the bile ducts. Ludwig86 has therefore termed this change ischemic cholangiopathy.
Steatotic Patterns The steatotic patterns of drug-induced liver injury include both microvesicular and macrovesicular steatosis as well as steatohepatitis (see Table 24-8). Macrovesicular steatosis may be observed as one component of another pattern of injury, such as zonal necrosis, as shown in the acetaminophen toxicity example of Figure 24-8. In such cases, the injury should be classified as the other pattern rather than as a steatotic pattern. Nonalcoholic fatty liver disease (NAFLD) and its alcohol-induced counterpart are the main etiologic alternatives for drug- or toxin-induced steatosis. As the prevalence of NAFLD rises in the general population, ascribing steatosis to a direct drug effect becomes more and more difficult. Nevertheless, there are some drugs, such as corticosteroids and methotrexate, that are clearly associated with steatosis. Like NAFLD, macrovesicular steatosis is often accompanied by a mild lobular or portal inflammatory infiltrate. The presence of other features, such as
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Figure 24-15. Chronic cholestatic hepatitis due to cefuroxime. Cephalosporins only rarely cause hepatic injury, and when they do, it is often a cholestatic jaundice, as is the case in this example of injury due to cefuroxime. Overall the biopsy shows changes reminiscent of chronic autoimmune hepatitis, but with some notable and unusual features. (A) The portal areas show a relatively mild lymphocytic infiltrate with prominent ductular reaction and cholate stasis (pseudoxanthomatous change) in the periportal hepatocytes. The ducts were intact although some show injury. (B) The chronic cholestatic changes are corroborated by a positive copper stain (rhodanine). (C) In addition to the portal inflammation, there is zone 3 necrosis, which is associated with a prominent plasma cell infiltrate. (D) A Masson trichrome stain shows areas of bridging fibrosis involving portal areas and central veins.
c holestasis or severe necroinflammatory changes, would suggest a mixed pattern of injury in which the steatosis may not even be related to the suspect agent (Fig. 24-16). Features of ballooning hepatocellular injury, perisinusoidal fibrosis, and Mallory body formation are characteristic of steatohepatitis. Drug-induced steatohepatitis has been attributed to a number of agents. Amiodarone and perhexiline cause a form of steatohepatitis associated with phospholipidosis (Fig. 24-17), which is an accumulation of lipid membrane material within the lysosomes of macrophages, not unlike a storage disease. Phospholipidosis may be generalized and affect other sites than the liver.87–89 Other drugs, such as methotrexate, tamoxifen, and the corticosteroids (Fig. 24-18), may exacerbate preexisting steatohepatitis or may develop a synergistic toxic effect with alcohol. The protease inhibitor class of antiretrovirals has been associated with a systemic syndrome of dyslipidemia, fat maldistribution, and insulin resistance that may secondarily cause steatosis and steatohepatitis.90 As with nonalcoholic and alcoholic steatohepatitis, drug-induced macrovesicular steatosis and steatohepatitis are chronic, generally lowgrade injuries, but at least in the case of steatohepatitis, serious liver disease in the form of cirrhosis may develop subclinically.91,92
Microvesicular steatosis is a more serious lesion that often presents with hepatomegaly and hepatic failure. It is almost always the result of a drug or toxic injury, frequently involving the mitochondria and leading to lactic acidosis. Histologically, microvesicular steatosis is characterized by a diffuse foamy change in the hepatocytes (Fig. 24-19). Mild inflammation, intrahepatic cholestasis, and individual hepatocyte apoptosis may be seen, but usually there is no massive necrosis as seen in severe acute hepatitic injury, which may present clinically in a similar fashion. A number of drugs have been associated with microvesicular steatosis and hepatic failure, most notably acetylsalicylic acid (Reye syndrome),93 valproic acid,94 the tetracylines,95 and some nucleoside analogs.96,97 The injury may continue to progress, even after the patient has stopped taking the drug. In the case of fialuridine, a nucleoside analog, hepatic failure developed in some patients weeks after they had stopped the drug.98,99 The mechanism of injury in microvesicular steatosis has been linked to the uncoupling of oxidative phosphorylation with some agents,100 whereas fialuridine is associated with damage to mitochondrial DNA.101 341
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Figure 24-16. Steatosis associated with risperidone. In this patient, risperidone therapy was associated with significant weight gain and the development of elevated liver enzyme tests. The biopsy showed marked macrovesicular steatosis in a distribution that spared the hepatocytes adjacent to the portal areas. There was only mild spotty lobular inflammation and no fibrosis or ballooning injury that would suggest steatohepatitis. In this case, the steatosis was probably not a direct effect of the drug but was more likely to be related to the associated weight gain on therapy.
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no longer lined by endothelium. Most agents that have been associated with peliosis also cause sinusoidal dilation, either as an isolated lesion or in areas of the liver unaffected by peliosis. Oral contraceptives in particular have been associated with the peculiar pattern of zone 1 sinusoidal dilation. Fatal hepatic hemorrhage has occurred in patients with peliosis. Nodular regenerative hyperplasia (NRH) is a chronic and subtle lesion induced by some of the same agents that cause more overt forms of vascular injury. Biopsies may look almost normal on routine stains, and failure to recognize NRH may lead to unnecessary clinical workup and even splenectomy, which worsens any existing portal hypertension.108 Any “normal” appearing liver biopsy should be evaluated with trichrome and reticulin stains, particularly if the clinical team is trying to rule out cirrhosis. The reticulin stain will show the most diagnostic changes, with widened, two-cell thick liver cell plates containing large hepatocytes alternating with small, atrophic liver cells in compressed one-cell thick plates (Fig. 24-22). The trichrome stain will often show a mild to moderate degree of perisinusoidal fibrosis in the zones of compression. Sinusoidal dilation may also be present. The portal areas should also be carefully examined for evidence of portal venopathy, with slitlike or obliterated portal veins. NRH has been associated with chronic therapy with immunosuppressive agents such as azathioprine (renal transplantation),109,110 thioguanine, and mercaptopurine (Crohn disease).111 Megadoses of vitamin A have been associated with noncirrhotic portal hypertension characterized by sinusoidal fibrosis and the accumulation of lipid-laden stellate cells.112,113
Vascular Injury Patterns
Pigments and Other Cytoplasmic Changes
A variety of vascular injury patterns have been associated with drug and toxic injury (see Table 24-7). They are interrelated in that drugs that cause one type of vascular injury are often associated with others. The main types of injury include veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), hepatic vein thrombosis (or BuddChiari syndrome), peliosis hepatis, sinusoidal dilation, and nodular regenerative hyperplasia (see Table 24-8). Two of these patterns, VOD/ SOS and hepatic vein thrombosis, may cause hepatic necrosis secondary to hypoxic injury from venous outflow obstruction. In VOD/SOS, there is obliteration of the small hepatic veins and obstruction of the sinusoids by cell debris.102 The sinusoidal injury is difficult to recognize on routine histologic sections, but the secondary changes of hemorrhage and hepatocellular necrosis should cause the observer to look closely at the veins. The veins will be narrowed by loose connective tissue and a Masson trichrome stain can be helpful in showing the normal vein wall as a thin blue rim around the reddish-blue connective tissue plug (Figs. 24-20 and 24-21). In hepatic vein thrombosis, the larger veins are occluded by thrombi. Because a large-caliber vein may not be sampled in a percutaneous needle biopsy, the biopsy may only show the secondary changes of marked congestion, central hemorrhage, and necrosis. Chemotherapeutic agents have been associated with both hepatic vein thrombosis and VOD/SOS, whereas oral contraceptives have been associated with hepatic vein thrombosis. Pyrrolizidine alkaloids, which are still found in a number of herbal and medicinal teas, were one of the first substances to be associated with VOD/SOS following an outbreak of this disease in Jamaica in the 1950s.103 Although in the context of chemotherapy and bone marrow preparative regimens, VOD/SOS often has an acute presentation, and chronic low doses of environmental toxins such as the pyrrolizidine alkaloids can lead to a chronic injury with fibrotic obliteration of the terminal veins.104 Over time, this can lead to a pattern of fibrosis similar to cardiac sclerosis. Both oral contraceptive steroids and anabolic steroids have been associated with peliosis hepatis and sinusoidal dilation.105–107 In peliosis, the sinusoids are transformed into cystlike spaces that are
Drugs may be associated with a number of cytoplasmic changes and pigment accumulation of varying clinical significance. Barbiturates and some other drugs have been associated with a ground-glass cell type of change due to a diffuse hypertrophy of the smooth endoplasmic reticulum.114,115 This may represent an induced adaptive change in the hepatocytes but may be alarming because patients can have hepatomegaly and elevated levels of gamma glutamyltransferase. It can be easily differentiated from the ground-glass cell change of hepatitis B by specific immunoperoxidase staining for surface antigen. Diffuse hepatic glycogenosis, or glycogenotic hepatopathy, is a cytoplasmic change in which the hepatocytes are swollen and pale but not vacuolated as in steatosis. There is usually little or no inflammation (Fig. 24-23). Glycogenosis can be associated with markedly elevated transaminase levels and hepatomegaly, which can trigger biopsy. It has been associated with short courses of high-dose corticosteroids116 and has also been recently reported in patients with type 1 diabetes.117 Both the diabetic and steroid associations suggest that dysregulated glycogen metabolism may be the cause of the change. Ground-glass inclusion bodies that react positively with periodic acid–Schiff (PAS) reagent after diastase digestion have been reported after cyanamide therapy. The inclusions are eosinophilic and have a narrow halo. On ultrastructural examination, the inclusions appear to be a conglomeration of glycogen, secondary lysosomes, lipid vesicles, and degenerating organelles.118 The lesion has been reported in association with cirrhosis, although it is not clear that the cirrhosis is not due to underlying alcoholic liver disease. Finally, there is a type of hepatocellular inclusion that is intensely PAS-positive but diastase-sensitive that has been associated with polypharmacotherapy and/or disordered glucose metabolism.119 A number of pigments have been associated with drug- and toxininduced liver injury in addition to bilirubin (discussed above) and iron. Lipofuscin may be increased after long-term therapy with chlorpromazine and other anticonvulsants, phenacetin, and Cascara sagrada.63,120 Increased cell death in drug injury reactions results in the accumulation of pigment in Kupffer cells, which can be highlighted with PAS staining.
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Figure 24-17. Amiodarone toxicity. Amiodarone is associated with two distinct presentations of hepatotoxicity. The better known to pathologists is the chronic injury pattern that can mimic steatohepatitis and result in cirrhosis. Amiodarone is also associated with a fulminant acute hepatitis that may develop following high dose intravenous administration. (A) This case shows cirrhosis with small regenerative nodules and mild inflammation, mainly confined to the fibrotic bands. There is very little steatosis visible and thus resembles many other cases of end-stage liver disease from more common etiologies. (B) Focally there is ballooning injury of hepatocytes similar to that seen in alcoholic or nonalcoholic steatohepatitis. Mallory bodies are present in the adjacent cells but are difficult to identify because they blend in with the granular eosinophilic cytoplasm. (C) Ubiquitin staining demonstrates numerous Mallory bodies, present in both ballooned and nonballooned hepatocytes (antiubiquitin). (D) In a separate case of amiodarone toxicity, there is microvesicular steatosis associated with Mallory body formation and prominent perisinusoidal fibrosis.
Black, granular pigments have been reported in the liver following the use of gold compounds121,122 or after abuse of laxatives containing mercurous chloride.123 Intravenous drug abuse may lead to the accumulation of black titanium pigment.124 Polyvinylpyrrolidone may accumulate in hepatic macrophages as a granular basophilic pigment.125 It stains positively with Congo red (negative birefringence), Sirius red, and Lugol iodine solution. The most notorious drug-associated pigment is thorium dioxide, which is better known by its trade name of Thorotrast. Thorotrast was used as an x-ray contrast medium from the 1930s into the 1950s. It appears as a gray-golden, partly refractile, coarsely granular pigment in Kupffer cells and sometimes free in the extracellular matrix.126 The radioactive alpha particles emitted by Thorotrast have caused hepatocellular neoplasms of all types (Fig. 24-24).
Neoplasms A few agents have been associated with neoplasia, both benign and malignant neoplasms (see Table 24-8). With the exception of Thorotrast, which leaves evidence of its existence, there is nothing about these
eoplasms to suggest a drug or toxic origin. Thus, drug-associated n neoplasia is mainly an epidemiologic issue rather than a histopathologic one. Anabolic and contraceptive steroids have been associated with nearly the full range of neoplasms, from hepatic adenomas to hepato cellular carcinoma, cholangiocarcinoma, and angiosarcoma.127–130 There is no convincing association between contraceptive steroids and the development of focal nodular hyperplasia.131 Occupational exposure to vinyl chloride has been implicated as a cause of angiosarcoma132,133 as well as other lesions of endothelial injury such as peliosis hepatis, sinusoidal dilation, and portal fibrosis with portal hypertension.104
Grading and Staging With the exception of methotrexate, there are no specific grading and staging systems in use for drug-induced liver injury. For methotrexate, the method of Roenigk and associates134 has been in use for several decades and is still used as part of the decision to continue methotrexate therapy. The use of liver biopsy in managing methotrexate therapy 343
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A
A
B
B Figure 24-19. Microvesicular steatosis due to fialuridine toxicity. Microvesicular steatosis is a rare but often devastating form of liver toxicity. It is often associated with mitochondrial toxicity that may be present in other organs as well. Lactic acidosis results from a switch to anaerobic metabolism and may be fatal. Fialuridine causes mitochondrial injury by inhibition of mitochondrial DNA polymerase and by incorporation into the DNA polymer. (A) The hepatocytes are swollen and pale due to the accumulation of lipid. Only mild lobular inflammation and only rare apoptotic hepatocytes are seen. (B) The hepatocytes have a foamy appearance at high magnification. The nucleus is not displaced by the microvesicles. Despite the viable appearance of the hepatocytes, the cells are metabolically crippled, leading to fulminant hepatic failure.
C Figure 24-18. Steatosis and fibrosis related to methotrexate therapy. Chronic methotrexate therapy for collagen-vascular diseases has been associated with the development of steatosis and progressive fibrosis. Portal inflammation with interface hepatitis may also be present. The risk of fibrotic progression varies with dosage, schedule, and total dose. Patients with psoriasis may be at greater risk, but there is definitely increased risk in patients who are both obese and diabetic as well as in those with chronic alcohol consumption. Biopsies are still performed to assess progression of liver disease. (A) This surveillance biopsy shows moderate macrovesicular steatosis and little inflammation. (B) Trichrome staining reveals mild sinusoidal fibrosis. Mallory bodies and ballooning hepatocellular injury are not seen. (Masson trichrome.) (C) Staining for smooth muscle actin demonstrates positive staining consistent with stellate cell activation in the area of fibrosis. (Anti–smooth muscle actin.) 344
is an issue that is debated in the literature.135 The staging scheme is shown in Table 24-9. Although no general scheme for grading and staging drug-induced liver disease exists, it seems reasonable to adopt other existing liver disease staging systems to help describe the disease severity. Histologic features that deserve descriptive quantitation include the degrees of fibrosis, ductal paucity, hepatocellular necrosis, and inflammation (including the presence or absence of bridging necrosis).
Differential Diagnosis Drug-induced liver injury is a diagnosis of exclusion. To make the diagnosis, one must first consider the possibility. If drugs and herbal agents do not ever enter a differential diagnosis, then they can never be identified as the cause of the injury. Once considered, there are a number of other factors to consider in the evaluation of any particular injury. No pathology report should ever read merely “consistent with drug injury”
Liver Injury Due to Drugs and Herbal Agents
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A
A
B
B
Figure 24-20. VOD/SOS due to melphalan. Local-regional therapies for cancer offer the possibility of increasing the chemotherapeutic dose delivered to the tumor while sparing the rest of the body from side effects. In this case, VOD/SOS developed within weeks after an isolated intrahepatic perfusion with melphalan for metastatic colon cancer. (A) The central vein is narrowed, with only a small slitlike lumen remaining. A few extravasated red cells are seen around the edges of the vein, but there is no necrosis. Intrahepatic cholestasis is also present. (B) The trichrome stain clearly shows that the vein lumen is filled with a pale-blue staining loose connective tissue. The original vein wall collagen stains a darker blue. (Masson trichrome.)
because all injuries are potentially drug-related. The report should identify the pattern(s) of injury that may be present and should include some estimate of the severity of the injury. Patterns can then directly lead to pathologic differential diagnosis as outlined in Table 24-7. This process should be done as objectively as possible to avoid being swayed by available clinical information. With the pathologic differential diagnostic possibilities determined, the pathologist and the clinician should work together to establish whether drugs or herbal agents are involved in the injury and what the likelihood of drug etiology is.
Determining Causality As noted in the introductory section, the establishment of a causal relationship between a particular agent and hepatic injury is a serious matter. Furthermore, it can be difficult to decide between various competing clinical factors. In response to this, hepatologists and other experts in drug-related injuries have devised a number of clinical point scales to help establish the degree of causality. The scales in common
C Figure 24-21. VOD/SOS after bone marrow transplant. VOD and SOS are serious complications of cytoreductive therapies used to prepare patients for bone marrow transplantation usually developing within the first 30 days after transplant. This patient developed VOD/SOS 1 month after bone marrow transplant for acute myelocytic leukemia. (A) There is coagulative necrosis of hepatocytes in zone 3 associated with hemorrhage. Sinusoidal dilation and congestion are seen outside the zone of necrosis. (B) Higher magnification of the same field shows occlusion of the central vein and surrounding sinusoids with fibrin and red cells. (C) By showing the collagen of the vein wall, the trichrome stain helps to identify the occluded veins within areas of necrosis, allowing the correct diagnosis of VOD/SOS. (Masson trichrome.) Both this patient and the patient with the intrahepatic perfusion (Fig. 24-20) died within a few weeks from complications of hepatic failure. 345
Practical Hepatic Pathology
A
B
C
D
Figure 24-22. NRH due to chemotherapy. Chemotherapeutic agents are associated with a variety of lesions, including VOD/SOS, peliosis hepatis, sinusoidal dilation, and NRH. In this patient with colon cancer, the only risk factor for NRH was systemic chemotherapy. The liver was diffusely nodular on gross examination. (A) At low power, the hepatic parenchyma has a vague nodular appearance, accentuated by staining variation and sinusoidal congestion. The smaller, atrophic hepatocytes are more deeply eosinophilic than the larger hepatocytes in the regenerative areas. (B) The key to the diagnosis is the observation of alternately expanded and compressed liver cell plates on a reticulin stain. As with the routine stain, there is subtle staining variation at low magnification, with darker staining in areas where the cords are narrowed. (C) At high magnification, the nodularity is clear on the reticulin stain, with alternating zones of liver plate expansion and compression. (D) The trichrome stain frequently shows some degree of sinusoidal fibrosis in the atrophic zones, but significant fibrosis suggestive of cirrhosis is not present. (Masson trichrome.)
use are outlined in Table 24-10. Two are liver specific, the RUCAM7 and the Clinical Diagnostic Scale, or CDS.136 The Naranjo scale is not specific to the liver but is meant to be used in the evaluation of any drugrelated injury.137 All of these scales consider a similar set of factors: the timing of drug use with respect to the injury, exclusion of other potential reasons for the injury, the resolution (or lack thereof) with removal of the agent, result on rechallenge (if done), and what has been reported in the literature concerning toxicity of the agent. The Naranjo scale also considers “objective evidence” of injury, such as a biopsy, but the two liver-specific scales do not include any factors for pathology data. The scales are also not very drug specific, although they do take into consideration whether the drug has been previously reported to cause injury and if there have been multiple reports of injury. The RUCAM does treat the different biochemical injury types somewhat differently in terms of the time to the onset of injury and the clinical course. Because these scales are clinical in their orientation and do not take into consideration the pathologic pattern of injury, they are not very satisfying to the pathologist. It is still important to have a systematic 346
approach to evaluating the pathologic and clinical features of any particular case so that one can arrive at an appropriate conclusion. Dr. Irey, who was chair of the Department of Environmental Pathology at the Armed Forces Institute of Pathology, devised such a method years before the clinical scales described previously were published.138 His method is outlined in Box 24-3. Temporal Eligibility This is the first consideration. One needs to gather information about all of the potential agents, drugs and herbal, that might account for the injury. It is important to know when the agent was started, when it was stopped, and when the injury was first noted. The date of onset may precede the date the patient was admitted to the hospital or when the first laboratory studies were drawn. Agents begun after the onset of injury may be excluded from consideration. Although this may seem an obvious point, there is usually some confusion about exactly when drugs were started as well as some difficulty pinpointing the date of onset. With some rare exceptions, drugs that have been taken for
Liver Injury Due to Drugs and Herbal Agents
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A
B
C
D
Figure 24-23. Steroid-induced glycogenosis. Corticosteroids are most commonly associated with development of steatosis in the liver. One of the rarer and potentially more significant injury patterns is hepatocellular glycogenosis, or glycogenic hepatopathy, which can develop after a short course of high-dose steroids. In this case, high-dose steroids were used to treat presumed hepatic graft-versus-host disease. The transaminases initially fell but rose abruptly after several days of therapy, prompting a liver biopsy. (A) The hepatocytes show cytoplasmic clearing, with only rare steatotic vacuoles. The change involves the entire lobule in this case. There is very little inflammation and no duct injury to suggest graft-versushost disease. (B) At higher magnification, one does not see the microvacuolation of microvesicular steatosis and the cytoplasm is not quite optically clear. Instead the “clear” spaces contain a very pale blue-gray material. (C) The cytoplasm stains intensely with periodic acid–Schiff, and this staining disappears completely after diastase digestion. (D) A second liver biopsy done 7 weeks later showed graft-versus-host disease but no evidence of glycogenosis.
many years without evidence of toxicity may be excluded as well. Some drugs, such as methotrexate, may cause a subclinical injury that does not present symptomatically until the patient has developed cirrhosis. Nitrofurantoin is another agent that may be taken for many months prior to the apparent onset of injury. Most drugs that cause injury will have been started within the past 3 months preceding the onset of injury, with some differences between the hypersensitivity and metabolic idiosyncratic agents as noted earlier. The patient may have stopped taking the medication up to a month prior to the onset of injury, and this gap does not necessarily exclude the drug from consideration. Exclusion of Competing Causes The second consideration is exclusion of competing causes. This requires a thorough clinical evaluation, including an extensive history, physical examination, and appropriate laboratory and imaging tests. The pathologic pattern of injury may help define what other diseases should be considered and excluded. The pathologic pattern may also exclude preexisting diseases or other nondrug etiologies from consideration.
For example, zone 3 confluent necrosis and canalicular cholestasis would not be compatible with chronic hepatitis C, and at the very least, they suggest that some other process is occurring. Known Potential for Injury and Precedent for Pathologic Injury Pattern The known potential for injury is an important piece of information to have, and it is a prelude to the next factor—the precedent for the pathologic injury pattern. The known potential injury relates to the incidence of injury, which is a difficult number to know with any precision. Nevertheless, reference to Table 24-8 or to any of the standard texts of drug-induced liver injury cited in the historical overview can be a good start. Beyond that, it has become a relatively simple matter to perform electronic searches of the literature. Combining the generic name of the drug with another search term such as hepatitis, hepatotoxicity, cholestasis, jaundice, or hepatic failure is usually a good way to start. Using a web-based search engine also gives the searcher access to FDA reports, books that are electronically searchable through access 347
Practical Hepatic Pathology Table 24-10. Causality Scoring Methods Author
Comments
Naranjo et al137 Not liver specific
A
Factors Considered in Method Prior reports of toxicity, timing, dechallenge, rechallenge, alternative explanations, toxicology, drug cross-reactivity, objective evidence
Danan and Benichou7
RUCAM—liver Biochemical injury type, timing of drug intake specific prior to onset and time to biochemical resolution, risk factors, age, other drugs, exclusion of other liver diseases, prior reports of toxicity, rechallenge
Maria and Victorino136
CDS—liver specific
Timing of drug intake prior to onset and time to biochemical resolution, exclusion of other liver disease, extrahepatic signs, rechallenge, prior reports of toxicity
CDS, clinical diagnostic scale; RUCAM, Roussel Uclaf Causality Assessment Method.
agreements, and other publicly available information. Drugs that are commonly used and have been on the market for many years with only rare reports of toxicity should not be considered equally with drugs that are more frequent causes of hepatitis injury. The same sources can provide information on the characteristic pathology. Most drugs have a relatively restricted spectrum of injury. Even when a particular agent has more than one pattern, usually there are some kinds of injury that are more common than others. For example, zonal necrosis is a much more common pattern of acetaminophen injury than the other injuries noted in the literature.
B Figure 24-24. Hepatic angiosarcoma due to Thorotrast. Thorotrast is a contrast agent that became notorious for its association with a variety of hepatic malignancies. This patient developed and later died from a hepatic angiosarcoma. (A) The sinusoids of the liver are infiltrated by a poorly differentiated spindle cell malignancy. Within the portal area and some of the nearby sinuses are cells that contain a pale golden refractile pigment. (B) The pigment accumulates in Kupffer cells of the liver, irradiating the nearby cells with alpha particles from the radioactive decay of the thorium. Its distinctive color and lack of staining for iron makes this pigment easy to identify as Thorotrast on routine sections.
Dechallenge/Rechallenge The factor of dechallenge refers to the idea that if a drug is causing an injury and the patient stops taking the drug, then the injury should subside. When this happens, it is circumstantial evidence of a causal relationship. However, there are many circumstances when the injury continues to the point of liver failure or, in the case of drug-related cirrhosis, may not be particularly reversible. Thus, persistence or worsening of the injury after cessation of the drug does not provide evidence for or against the drug. Rechallenge occurs rarely but is sometimes necessary when the drug is critical or not easily replaced by another agent. In the case of herbal medications, patients sometimes rechallenge
Box 24-3. Practical Considerations in Determining Causality (after Irey) Table 24-9. Staging of Methotrexate-Related Injury Stage
Description
I
Normal to mild nonspecific changes of steatosis, anisonucleosis, and portal inflammation
II
Moderate to severe steatosis, anisonucleosis, and inflammation with fibrosis up to portal fibrotic expansion
IIIA
Formation of fibrous septa
IIIB
Moderate to severe fibrosis (bridging)
IV
Cirrhosis
Adapted from Roenigk HH Jr, Auerbach R, Maibach HI, et al: Methotrexate in psoriasis: Revised guidelines. J Am Acad Dermatol. 1988;19:145–156.
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Factors to consider • Temporal eligibility • Exclusion of competing causes • Known potential for injury • Precedent for pathologic injury pattern • Dechallenge/rechallenge • Toxicologic analysis Classification by degree of certainty • Definite—Classic presentation by known toxin, no competing causes • Very likely—Nearly classic presentation, no competing causes • Probable—Classic/near-classic presentation, not all competing causes can be absolutely excluded or toxin without precedent but for which there are no competing causes • Possible—Atypical presentation or competing causes, but some features in favor of toxicity • Excluded—Agent can be reasonably excluded from consideration From Irey NS: Teaching monograph. Tissue reactions to drugs. Am J Pathol. 1976;82:613–647.
Liver Injury Due to Drugs and Herbal Agents t hemselves out of ignorance. In any case, if rechallenge causes the injury to recur, then that is excellent evidence in favor of causation. Toxicologic analysis, the last item in Irey’s method, may be useful in certain limited circumstances, but generally only if the drug is an intrinsic hepatotoxin, such as acetaminophen. For idiosyncratic toxicity, toxicology is of little value. Degree of Certainty Once these factors have been taken into consideration, one should try to assign a level of certainty to the diagnosis (see Box 24-3). Although this may not be a formal part of the diagnostic line, some part of the case discussion should focus on how likely the drug is to have caused the injury based on pattern and presentation. Drugs with No Record One final comment concerns agents that have no record of injury. This is particularly true of drugs recently added to the pharmacopeia or that are experimental agents in clinical trial situations. Herbal formulations may fall into this category as well. In these situations, most of the arguments based on pattern and precedent are difficult if not impossible to apply. One must therefore depend on careful exclusion of competing causes and examination of the pathologic changes for features that might be more suggestive of drug or toxic injury. Evaluation of injuries caused by agents of the same class is sometimes helpful. In the case of experimental agents, determination of causality is critical. It is just as important to correctly identify another etiology and exonerate the experimental agent as it is to incriminate it and cause it to be removed from clinical use.
Ancillary Diagnostic Studies Patients under evaluation for drug-induced liver injury should have a clinical evaluation that is sufficient to exclude other causes of liver disease as discussed previously. This could include serologic testing for viruses and autoantibodies as well as ceruloplasmin and alpha-1 antitrypsin levels. Molecular testing for viruses may be needed in cases of acute hepatitis to fully exclude a viral infection. The testing may have to be performed during the follow-up period, as in the case of hepatitis C virus; molecular and serologic tests may be negative during the acute phase of the illness. Imaging studies should be done as appropriate to exclude biliary obstruction and to evaluate the biliary tree for evidence of sclerosing cholangitis. The pathologist’s evaluation should be just as thorough in order to characterize the injury completely. If a patient goes for liver transplant or dies and an autopsy is performed, a small piece of liver can be frozen and set aside for biochemical or molecular studies. With a biopsy, the options for use of the tissue are more limited, but one should consider trimming a small piece for ultrastructural evaluation and/or fat stains. Fat stains may be performed on the formalin-fixed biopsy by cutting sections from the fixed tissue on a cryostat prior to processing. Depending on laboratory practice, it would be prudent to cut additional unstained sections from the biopsy at the time of first cutting in order to conserve tissue. One should have a low threshold for using special stains to evaluate drug-induced liver injury. Trichrome stains or similar collagen stains should be done almost as routinely as hematoxylin and eosin to evaluate the degree of fibrosis and discriminate between established scarring and areas of necrotic collapse. They are also useful for evaluating the veins in occlusive diseases. Reticulin stains should be done to establish the diagnosis of NRH. Iron and copper stains are not only useful for evaluating for those metals but also useful to show bile accumulation in hepatocytes and canaliculi. PAS stains can be used to characterize cytoplasmic inclusions. Acid-fast, methenamine silver, and Warthin-Starry stains should be done to help exclude unusual
infections when granulomas are present. Among the immunostains, cytokeratins 7 and 19 are useful for highlighting biliary epithelium and may help identify duct remnants obscured by inflammation or that are so damaged that they are difficult to recognize. Ubiquitin staining highlights Mallory bodies. Stains for hepatitis B will probably be useful only if the patient is known to have hepatitis B or if ground-glass cell change is focal. In situ hybridization for Epstein-Barr virus may be needed if the mononucleosis pattern is seen. Immunohistochemical phenotyping of the lymphocytes or molecular studies may be necessary to exclude lymphoma. As always, careful forethought about which stains to perform as well as conservative use of the tissue is important in the pathologic evaluation of possible drug injury.
24
Genetics There are a number of recognized genetic factors associated with susceptibility to increased injury from drugs. Genetic differences between individuals provide one of the mechanistic explanations of idiosyncratic hepatotoxicity. Halothane was one drug in which early evidence suggested a genetic component both in humans and in animal models. Otsuka and coworkers identified human leukocyte antigen (HLA) associations in Japanese patients who developed halothane hepatitis.139 In that population, the DR2 locus was more common and the Bw44 locus was less common in patients with jaundice. HLA associations have been reported in amoxicillin-clavulanate injuries from patients in Belgium140 and Scotland.141 These groups independently identified the DRB1*1501 locus as associated with injury from this antibiotic. Other drugs with injuries associated with HLA antigens include nitrofurantoin,142 clometacin,143 chlorpromazine, diclofenac, and the tricyclic antidepressants.144 Defects in drug-metabolizing enzymes have also been associated with a predisposition to hepatotoxicity with certain drugs. These include defects in the cytochrome P450 family of enzymes and in other processing enzymes that are responsible for detoxification of drugs. Deficiency of CYP2D6 has been associated with toxicity from perhexiline.145 Enhanced activity of this enzyme has been correlated with chlorpromazine injury in conjunction with defects in sulfoxidation.146 Deficiency of the N-acetyltransferase-2 (NAT2) enzyme lies at the root of the slow acetylation phenotype. Individuals who are NAT2-deficient have increased susceptibility to injury from the sulfonamides147,148 and dihydralazine.59 The recent sequencing of the human genome and the completion of the National Human Genome Research Institute’s HapMap project have sparked interest in using large-scale single nucleotide polymorphism analysis to identify people who might be susceptible to drug injury of all types. This approach would complement the targeted gene methods used in the studies described earlier. At this point, the major barrier to whole genome screening lies in accrual of sufficient numbers of validated cases and controls so that the genomic analysis is meaningful.149
Treatment and Prognosis The first treatment for drug-induced liver injury is to stop the administration of the suspect agent. This usually occurs as soon as there is a suspicion that a drug may be involved and therefore is usually done before a biopsy is performed. Sometimes a drug is continued until a biopsy is performed and the degree of injury can be assessed, as in the case of methotrexate. More rarely, the biopsy suggests a diagnosis of drug injury that had not previously been considered, and so the drug is stopped only after the biopsy has been performed. Many injuries will resolve once the drug has been stopped, and the speed of recovery depends on the type of injury and the overall severity. General supportive therapy for liver injury is used on a case-by-case basis. Not all drug injuries have the same prognosis. The late Dr. Hyman 349
Practical Hepatic Pathology Zimmerman propounded a rule of thumb based on his clinical experience that jaundice in the presence of a hepatocellular injury (elevated transaminases) was the most serious injury and resulted in approximately 10% mortality.5 This rule, known as “Hy’s law,” has recently been tested and shown to be essentially correct. Two large-scale studies, one in Spain9 and one in Sweden,150 evaluated mortality as a function of biochemical presentation. In the Spanish study, 11.7% of patients with hepatocellular jaundice progressed to liver transplantation or death, whereas in nonjaundiced patients with hepatocellular injury the figure was only 3.8%. In the Swedish study, 12.7% of patients with hepatocellular injury were either transplanted or died, compared with 7.8% of patients with cholestatic injury. Of the patients with hepatocellular injury, those that died or received transplants were older and had higher bilirubin levels, higher AST and ALT, and a higher ratio of AST to ALT. Transplantation has been used since its inception for acute liver failure due to drugs and toxins. Using the UNOS registry data, it was estimated that about 15% of transplants for acute liver failure between 1990 and 2002 had drug injury as a cause. Nearly 50% of those cases were due to liver failure from a single drug, acetaminophen.36 There are few specific interventions that are used in drug-induced liver injury. N-Acetylcysteine has been used for 40 years to counter acetaminophen toxicity by replenishing depleted stores of glutathoine.151,152 The efficacy of this agent in acute liver failure from other causes is being investigated at this time by the Acute Liver Failure Study Group.153,154 Corticosteroids are sometimes used to treat drug-induced liver injury, particularly hypersensitivity types of idiosyncratic injury, but there are no controlled clinical trials that have confirmed the efficacy of steroid therapy in this situation. The prognostic significance of the histologic findings on biopsy has not been broadly examined in drug-induced liver injury and most would apply what is known about liver disease in nondrug injury etiologies to the drug injury situation. Cirrhosis and massive hepatocellular necrosis portend a poor outcome no matter what etiology is responsible. One interesting study surveyed the opinions of 29 expert hepatologists concerning 39 clinical, biochemical, and pathologic disease features that were indications of severe drug-induced liver disease.155 Participants were asked rank features by severity. Of the top 10 features, 6 were pathologic findings: hepatocellular carcinoma, veno-occlusive disease, cirrhosis, sclerosing cholangitis, ductopenia, and bridging fibrosis. With respect to particular histologic features, Bjornsson and colleagues reviewed 570 case reports of drug-induced liver injury that had made note of eosinophilia (both peripheral and in biopsies) and hepatocellular necrosis on biopsy.156 Patients who survived were more likely to have eosinophils (in either site) and less likely to have hepatocellular necrosis. Katoonizadeh and associates looked at biopsies from patients in acute and subacute liver failure and found an association between poor outcome (death/transplantation) and the degree of hepatocellular necrosis, increased numbers of hepatocyte progenitor cells, and reduced numbers of proliferating hepatocytes.157 These findings are encouraging; other tissue-based prognostic factors may yet be discovered for drug- and herbal-induced liver injury.
Acknowledgments The photomicrographs in Figures 24-1 to 24-7, 24-9, 24-11 to 24-15, and 24-17 were obtained from cases referred to and confirmed by the Drug-Induced Liver Injury Network (https://dilin.dcri.duke.edu/). Suggested Readings oodman ZD. Drug hepatotoxicity. Clin Liver Dis. 2002;6:381–397. G Ishak KG, Zimmerman HJ. Morphologic spectrum of drug-induced hepatic disease. Gastroenterol Clin North Am. 1995;24:759–786.
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Kaplowitz N. Idiosyncratic drug hepatotoxicity. Nat Rev Drug Discov. 2005;4:489–499. Lee WM. Drug-induced hepatotoxicity. N Engl J Med. 2003;349:474–485. Wilke RA, Lin DW, Roden DM, et al. Identifying genetic risk factors for serious adverse drug reactions: Current progress and challenges. Nat Rev Drug Discov. 2007;6:904–916.
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Brief Historical Overview 311 Incidence and Demographics 312 Clinical Manifestations 313 Microscopic Pathology 315 Necroinflammatory Patterns 315 Cholestatic Patterns 336 Steatotic Patterns 340 Vascular Injury Patterns 342 Pigments and Other Cytoplasmic Changes 342 Neoplasms 343 Grading and Staging 343 Differential Diagnosis 344 Determining causality 345 Ancillary Diagnostic Studies 349 Genetics 349 Treatment and Prognosis 349
Abbreviations ALT alanine aminotransferase AST aspartate aminotransferase CDER Center for Drug Evaluation and Research CDS clinical diagnostic scale CIOMS Council for International Organizations of Medical Sciences DILIN Drug-Induced Liver Injury Network FDA Food and Drug Administration HLA human leukocyte antigen NAFLD nonalcoholic fatty liver disease NAT2 N-acetyltransferase-2 NIDDK National Institute of Diabetes and Digestive and Kidney Diseases NRH nodular regenerative hyperplasia PAS periodic acid–Schiff PBC primary biliary cirrhosis PSC primary sclerosing cholangitis
RUCAM ULN UNOS VOD/SOS
Roussel Uclaf Causality Assessment Method upper limit of normal United Network of Organ Sharing veno-occlusive disease/sinusoidal obstruction syndrome
Brief Historical Overview
In 1965, Hans Popper and his coworkers1 published a landmark paper entitled “Drug-Induced Liver Disease: A Penalty for Progress.” He reviewed 155 cases of apparent liver toxicity, related to 30 different agents. He recognized that the information on the clinical and pathologic characteristics of drug- and toxin-induced injury was poorly organized and would benefit from a systematic attempt at classification. He therefore proposed dividing the pathologic changes into six basic categories: zonal injury, uncomplicated cholestasis, nonspecific drug-induced hepatitis with or without cholestasis, reactions simulating viral hepatitis, nonspecific reactive hepatitis, and drug-induced steatosis. To a large extent, the classifications used today are intellectual children of Popper’s classification, reorganized and expanded. The major additions include the spectrum of drug-induced vascular injury, mainly a product of chemotherapy and certain natural products; subcategories of cholestatic liver disease related to primary or secondary destruction of the ducts; and the category of drug-induced hepatic neoplasms. Identification of the pattern of injury under the microscope is the first job of the pathologist, because the pattern of injury determines the pathologic differential diagnosis and helps determine the mechanism of injury. A significant barrier to gaining a comprehensive understanding of drug-induced liver injury is the medical literature itself. The primary literature of human drug-induced liver injury is mainly in the form of case reports and small series scattered across the full breadth of the medical literature. There is huge variation in the quality of individual articles both in terms of the data being presented (including descriptions of pathologic changes) and the extent to which other causes of liver injury are excluded. In addition, because of advances in hepatology during the past 40 years, we are now better able to diagnose a number of conditions that could be mistaken for drug injury. For example, prior to 1988, chronic hepatitis C may have been present and been mistaken for chronic drug-induced injury (a factor to consider in reading 311
Practical Hepatic Pathology older literature). Beyond the primary literature are a host of review articles, some of which are highlighted at the end of the chapter. These can be helpful, but most are written from a clinical point of view and are published in a wide range of clinical subspecialty journals. There are also a number of recent monographs devoted to drug- and toxininduced liver injury, and although these are also written from a clinical point of view, they can offer significant insight into the pathology of drug-induced liver injury.2–6 In recognition of the need to bring structure to what is essentially an anecdotal science, there have been a number of efforts in the past several decades to scientifically evaluate drug-induced liver injury in humans. Beginning in 1985, the European pharmaceutical company Roussel Uclaf organized a series of consensus meetings in France on adverse drug effects. These meetings considered fundamental questions of injury classification and causality. These efforts culminated in 1993 with the publication of the Roussel Uclaf Causality Assessment Method (RUCAM), which is a numerical scoring system designed to help clinicians assign a degree of certainty to whether a particular agent is responsible for a particular case of hepatotoxicity.7 This system is further considered below. In the United States, the Food and Drug Administration (FDA) Center for Drug Evaluation and Research (CDER) has organized a number of meetings since 2001 involving the FDA, academia, and the pharmaceutical industry, which discuss various aspects of drug-induced liver injury. Documents relating to these meetings are freely available on the FDA’s website (www.fda.gov/Drugs/ScienceResearch/ResearchAreas/ ucm071471.htm). Another recent development has been the establishment of regional and multicenter clinical networks devoted to gathering cases of drug-induced liver injury. Networks exist in France8 and Spain,9,10 in the United States, as well as in other countries. In the United States, the Acute Liver Failure Study Group (acsresearch.swmed.edu/ ALF/home.html) prospectively collects cases of acute liver failure, a significant percentage of which are due to drug-induced liver injury.11,12 The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) sponsored a U.S.-based Drug-Induced Liver Injury Network (DILIN; https://dilin.dcri.duke.edu/) that is actively accruing and characterizing cases of drug injury.13 Given the relatively low incidence of drug-induced liver injury (discussed later), one may justifiably wonder why it is so important to correctly identify and classify cases. One of the main reasons is that the subtle clinical presentation coupled with a potentially fatal outcome is of great concern to physicians and patients alike. Confirmed hepatotoxicity sometimes leads to regulatory action. Table 24-1 shows the drugs that have been either been removed from the U.S. market or flagged by black box warnings by the FDA for liver injury. A review of FDA regulatory actions over a 25-year period showed that liver injury was the most common reason for a drug to be withdrawn or have its use curtailed.14 Furthermore, every year, reports of first instances of hepatotoxicity of new drugs appear (Box 24-1), reinforcing the fact that we are unable to screen completely for potential hepatotoxicity in preclinical or clinical trial settings. Correct causal association of a drug with an injury coupled with properly reporting the injury is an important part of protecting patients and can lead to removing potentially harmful medications from the pharmaceutical armamentarium.
Incidence and Demographics It is difficult to assess the true incidence of drug-induced liver injury accurately for any particular agent. To know the incidence, one must have some information about the exposed population as well as some method of identifying all of the cases of injury. Both of these are subject to bias in data collection. Nevertheless, some statements can be made. In large, population-based studies, the overall incidence of drug-induced liver 312
Table 24-1. Hepatotoxicity Resulting in Food and Drug Administration Regulatory Actions Drugs Withdrawn
Black Box Warnings
Safety Alerts
Benoxaprofen
Dacarbazine
Acetaminophen
Bromfenac
Danazol
Leflunomide
Ticrynafen
Felbamate
Nefazodone
Troglitazone
Ketoconazole
Nevirapine
Pemoline
Pyrazinamide/rifampin
Tolcapone
Telithromycin
Trovafloxacin
Terbinafine
Valproate
Zafirlukast
Zalcitabine Zidovudine
Dietary supplements Kava Lipo KinetiX
Data from Lasser KE, Allen PD, Woolhandler SJ, et al: Timing of new black box warnings and withdrawals for prescription medications. JAMA. 2002;287:2215–2220; Watkins PB: Idiosyncratic liver injury: challenges and approaches. Toxicol Pathol. 2005;33:1–5; and Norris W, Paredes AH, Lewis JH: Drug-induced liver injury in 2007. Curr Opin Gastroenterol. 2008;24:287–297.
injury varies from about 2 to 150 per million person-years, depending on the population studied (Table 24-2). Drug classes frequently associated with hepatotoxicity include the antibacterials, particularly amoxicillinclavulanate and the sulfonamides; the antimycobacterials; nonsteroidal anti-inflammatory drugs; and antiseizure medications. In Singapore, herbal agents in the form of traditional Chinese medicines make up a significant proportion of cases.29,30 The prevalence of injury related to particular agents changes with time—Friis and colleagues examined 1100 adverse drug reactions reported to the Danish surveillance system from 1978 to 1987. During this time, the number of reactions due to halothane decreased, probably because of the reduced use of that anesthetic.31 Herbal usage by persons in the United States has risen progressively over the past 50 years,32 and although it is difficult to track the incidence of herbal-related liver injury, it is likely that cases will continue to rise in proportion to increased use. Liver injury accounts for a disproportionate amount of drug-associated mortality. In the Danish study, liver injury accounts for 5.9% of the adverse drug reactions but 14.7% of the deaths. Another study from New Zealand recorded similar findings. Surveys of acute liver failure (Table 24-3) show that druginduced liver injury usually accounts for a significant proportion of cases, from 15% of cases from the United Network of Organ Sharing Box 24-1. Drugs with Newly Reported Hepatotoxicity, 2005–2007 2008 Sorafenib15 Trastuzumab16 2007 Erlotinib17,18 2006 Anastrozole19 Atomoxetine20 Ezetimibe21 Telithromycin22 2005 Alosetron23 Bortezomib24
Liver Injury Due to Drugs and Herbal Agents Table 24-2. Estimates of the Incidence of Drug-Induced Liver Injury (DILI) Country
Years
Method of Case Accrual
Total Cases
Top Drugs Identified
Estimated Incidence of DILI (per million person-years)
United States25
1977–1981
HMO database
9
Ampicillin
2–4 for patients <40 years 20–80 for patients >60 years
Spain10
1993–1998
Referral
107
Acetaminophen, aspirin, ranitidine
7.4 (acute serious toxicity)
France8
1997–2000
Population-based
34
Augmentin, nevirapine, atorvastatin
140 (crude rate) 80 (standardized rate)
England26
1994–1999
Practice database
128
Acetaminophen, diclofenac, flucloxacillin
24 (with sixfold increased risk if two or more drugs suspected)
Spain9
1994–2005
Referral
461
Amoxicillin-clavulanate, ebrotidine, antimycobacterials
17 (severe toxicity) 34 (overall toxicity)
Sweden27
1995–2005
Practice database
77
Diclofenac, flucloxacillin, azathioprine
23
England28
1998–2004
Referral for jaundice
28
Amoxicillin-clavulanate, flucloxacillin
13 for jaundice-related DILI
24
HMO, health maintenance organization.
(UNOS) database36 to just over 50% of cases reported to the Acute Liver Failure Study Group.11 The proportion of drug-induced liver failure due to acetaminophen also varies considerably, from no cases in a Japanese cohort35 to 75% of cases in several U.S. and Canadian studies.11,38,41 Besides acetaminophen, other drugs that commonly top the lists include isoniazid, valproic acid, and halothane. Like incidence information, it is difficult to assess the demographic factors that are associated with drug-induced liver injury. Overall, the number of reports of drug-induced liver injury appear to increase with age,25,31 but whether this is due to true susceptibility or increased drug usage is not clear. In terms of specific drugs, children are more likely to be injured by aspirin42 and valproic acid43 and less likely to be injured by isoniazid,44 halothane,45 and erythromycin.46 For many drugs, there
is either insufficient information on age-related incidence or no apparent age effect. With respect to gender, studies show either more reports of liver-related drug injury in women31,33 or similar numbers between men and women.9 Women are much more likely to develop drug-associated autoimmune hepatitis than men, just as in idiopathic autoimmune hepatitis.47
Clinical Manifestations Hepatotoxic agents are classified clinically in several ways, but a common categorization is to divide them into intrinsic and idiosyncratic hepatotoxins (Table 24-4).48 Intrinsic hepatotoxins cause injury in a dose-dependent, reproducible manner that is usually testable in animal
Table 24-3. Drug-Induced Liver Injury (DILI) from Surveys of Acute Liver Failure Years
Method of Accrual
Fraction due to DILI (%)
Total Cases of DILI
Percent Acetaminophen Other Top Drugs
1991–1999
Hospital database
27
22
55
United States
1998–2001
Referral
52
160
75
Japan
1970–1998
Referral
95
0
Ecarazine, halothane
United States
1990–2002
UNOS database
270
46
Isoniazid, propylthiouracil, phenytoin, valproate
Sweden37
1966–2002
Adverse drug reports
103
14
Halothane, flucloxacillin, trimethoprim-sulfamethoxazole
United States, United Kingdom, Canada38
1999–2004
Pediatric referral
65
74
Valproate, isoniazid
WHO 39
1968–2003
Adverse drug reports
4690
6.5
Troglitazone, valproate, stavudine
Portugal40
1992–2006
Referral
23
14
0
Antimycobacterials, sulfasalazine, nimesulide
United States41
2000–2004
Population-based survey
54
35
77
Country Canada34 11
35 36
15
19
Isoniazid
UNOS, United Network of Organ Sharing; WHO, World Health Organization.
313
Practical Hepatic Pathology Table 24-4. Classification of Drug-Induced Liver Injury by Toxicity Category Category and Subcategory
Mechanism(s)
Intrinsic Direct Indirect
Idiosyncratic Immunologic
Metabolic
Toxin or metabolite reacts with multiple targets, resulting in massive disruption Drug metabolite disrupts specific metabolic pathway or selectively affects particular macromolecules
Other Features
Examples
Dose-dependent, can be reproduced experimentally Results in cell necrosis with usually little inflammation Effect depends on targets but usually pauciinflammatory
Carbon tetrachloride (hepatocytes), Paraquat (cholangiocytes) Acetaminophen (necrosis, steatosis), contraceptive steroids (cholestasis)
Low incidence, dose-independent, difficult to reproduce Drug metabolite reacts with macromolecules to Systemic symptoms and signs (fever, rash, form hapten for B- and T-cell mediated immune eosinophilia, autoantibodies), prompt responses recurrence to rechallenge Susceptibility to injury increased by genetic or acquired Variable time to onset, absence of immunologic inability to detoxify or eliminate injurious metabolites signs
models. They are further subclassified as either direct, in which the agent itself is the poison, or indirect, in which the agent is metabolized reproducibly to a toxic substance. Examples of direct hepatotoxins include carbon tetrachloride, which causes zone 3 necrosis and steatosis, and the herbicide Paraquat, which damages bile duct epithelium. Acetaminophen is a typical example of an indirect intrinsic hepatotoxin. Under normal conditions, it is adequately metabolized and excreted by the liver, but with high doses, increased induction of cytochrome P450 2E1, or reduced stores of cellular glutathione, it is metabolized to the active metabolite N-acetyl-p-benzoquinone, which can damage the cell.49 Finally, toxicity is classified by the target of the agent, usually either the hepatocyte, resulting in hepatocyte necrosis (usually along zonal lines), or the cholangiocyte, resulting in duct destruction. The injury caused by idiosyncratic hepatotoxins is unpredictable, not dose-dependent, and of low incidence compared with the intrinsic hepatotoxins. Idiosyncratic hepatotoxins are subdivided by mechanism of action into metabolic and immunologic hepatotoxins. Immunologic hepatotoxins share some common characteristics, including a drug sensitization period of at least 1 to 5 weeks prior to presentation with prompt recurrence of injury with rechallenge. They lead to hepatic injury that resembles autoimmune hepatitis or cholangitis. Systemic symptoms of fever, rash, and peripheral eosinophilia may be seen, and liver biopsies are more likely to have eosinophils or granulomas.50 Metabolic hepatotoxins differ from the immunologic hepatotoxins in several important respects. There is a widely variable latent period prior to the development of jaundice, and rechallenge does not cause immediate recurrence of the injury. The systemic features of hypersensitivity are absent in metabolic idiosyncrasy. Mechanisms of metabolic hepatotoxicity include genetic variation in pathways that process and detoxify drugs, competition for metabolic pathways by other drugs, or induction of pathways that lead to more toxic metabolites.51 The clinical presentations of drug-induced liver injury are almost as varied as the pathology. Patients may present in fulminant hepatic failure, with painless jaundice that mimics obstruction, with signs and symptoms of portal hypertension, with a mass lesion, or with asymptomatic enzyme abnormalities. The onset may be sudden or insidious. Because most drug reactions fall into either the necroinflammatory or the cholestatic categories, the biochemical changes in transaminases, bilirubin, and alkaline phosphatase are used to categorize the injury into a limited number of categories. In general, injuries that present mainly with transaminase (either alanine aminotransferase [ALT] or aspartate 314
Halothane, chlorpromazine, nitrofurantoin, erythromycins, phenytoin Isoniazid, valproic acid, amiodarone
aminotransferase [AST]) elevations are categorized as hepatocellular, whereas injuries characterized by elevated alkaline phosphatase are categorized as cholestatic. Injuries in which both transaminases and alkaline phosphatase are elevated are classified as mixed. This classification has been codified by the Council for International Organizations of Medical Sciences (CIOMS) at meetings organized by Roussel Uclaf. It is based on the ratio of ALT to alkaline phosphatase after normalization to the upper limit of normal for each test (Table 24-5).7,52 For the purposes of biochemical classification, the ratio is obtained from the time of onset of the injury. The ratio may vary as the injury progresses. If the patient is jaundiced, then that feature is added to the biochemical categorization. Thus, hepatocellular jaundice is an injury in which the transaminases are the predominant enzyme abnormality and jaundice is present. It is important to note that jaundice may be a component of any biochemical presentation and does not imply cholestatic biochemistries. It is also a mistake to extrapolate the biochemical pattern to the histologic findings. There is, at best, only a rough correlation between the biochemical categorization and the histologic patterns of injury described subsequently.53 Patients with a biochemically hepatocellular injury can have essentially any pathologic pattern on biopsy, including acute intrahepatic cholestasis with minimal inflammation. Biochemically cholestatic injury may show an acute lobular hepatitis pattern without evidence of cholestasis on biopsy. Thus, pathologic diagnostic terms such as hepatitis should be applied only if tissue is obtained for pathology review.52 Biopsies may be done for any of several reasons during the evaluation of drug-induced liver injury. Box 24-2 outlines some of the information that should be routinely evaluated in a liver biopsy done for drug injury. It is unusual to see a biopsy under circumstances Table 24-5. Biochemical Classification of Drug-Induced Liver Injury* Injury Category
Minimum Abnormality
R Values
Hepatocellular
ALT/ULN ≥ 2
R≥5
Mixed
ALT/ULN ≥ 2
2
Cholestatic
AP/ULN ≥ 2
R≤2
R = (ALT/ULN) ÷ (AP/ULN). ALT, alanine aminotransferase; AP, alkaline phosphatase; R, ratio; ULN, upper limit of normal. *Drug-induced liver injury is categorized based on the following equation:
Liver Injury Due to Drugs and Herbal Agents Box 24-2. Information Available from Liver Biopsies in Drug-Induced Liver Injury
• Determination of the pattern of injury • Correlation of injury pattern with published literature of particular agent • Assessment of the degree of injury (necrosis, duct paucity, fibrosis) • Identification or exclusion of other competing etiologies of liver disease • Pattern of injury may suggest mechanism of toxicity
where the diagnosis of drug injury is absolutely clear on clinical grounds. The clinical situation is therefore likely to be complicated by competing causes of liver injury or a complex drug history. In such a situation, the pathologist can help by carefully defining the pattern of injury and the pathologic differential diagnosis. A biopsy may also be done to rule out significant ongoing injury so that a critical drug may be continued. It is important to document the severity of the injury so that these kinds of clinical decisions can be made. On occasion, a liver biopsy may be done to evaluate enzyme changes or jaundice in a situation where drug injury is not suspected. In this case, the pathologist can play a significant role in bringing possible drug injury into the clinical differential diagnosis and helping to exclude other causes of liver disease.
Microscopic Pathology The diagnosis of drug-induced liver disease can be one of the most challenging and frustrating aspects of hepatic pathology. Essentially every pattern of liver disease may be observed, including patterns that are mixed and difficult to classify. Nevertheless, having a systematic approach to evaluating the liver biopsy and coupling that with identification of the pattern(s) of injury is the most fruitful approach. Although drug and herbal hepatotoxicity can replicate almost any nontoxic injury, individual agents do not usually show every kind of injury. Furthermore, it is important to remember that certain kinds of injuries are more often associated with drugs or toxic agents than other etiologies of liver disease (Table 24-6). Drug-induced liver injury should always be in the differential diagnosis when evaluating a liver biopsy, particularly one that is done to evaluate an as yet undiagnosed liver injury. Being alert to the Table 24-6. Histologic Features that Should Prompt a Search for Drug Injury Feature
Associated Drug Injury Mechanism
Eosinophils (prominent)
Hypersensitivity reactions
Granulomas
Hypersensitivity reactions
Zonal necrosis
Susceptibility to injury based on zonal variation in enzymes such as the cytochrome P450 family
Massive (fulminant) necrosis
Severe end injury of many drugs that cause intrinsic or idiosyncratic hepatocellular injury
Microvesicular steatosis
Mitochondrial injury
Vascular injury
Toxic injury to endothelial cells (acute and chronic) is associated with the entire spectrum of vascular injuries.
Mixed patterns Cholestasis + hepatitis Steatosis + necrosis
Mixed patterns suggest multiple cellular targets, a common effect of drug injury. Cholestatic hepatitis is a common pattern of idiosyncratic toxins, whereas steatosis and necrosis are observed with indirect hepatotoxins such as acetaminophen.
possibility of a toxic injury even when one is not suspected clinically can help keep the pathologist’s mind free of biases when reviewing a case. Hepatotoxic agents may injure any of the cell types in the liver: hepatocytes, cholangiocytes, endothelial cells, and even Kupffer cells. The primary cell type injured determines how the toxicity is manifested, particularly endothelial and cholangiocyte injuries. Primary injury to hepatocyte can result in necrosis, steatosis, and cholestasis. Inflammation can result either by involvement of the immune system in idiosyncratic hypersensitivity reactions or secondarily through recruitment of immune cells to sites of injury. A basic pattern-based classification of drug-induced liver injury is presented in Table 24-7 and an index to injury patterns caused by individual agents is given in Table 24-8. Pathologic terms such as hepatitis, cirrhosis, hepatocellular necrosis, and cholestatic hepatitis should not be used to describe a drug injury in the absence of pathologic confirmation.
24
Necroinflammatory Patterns It is frequently the case that patients with hepatotoxicity come to clinical attention because of the results of a necroinflammatory injury. A glance at Table 24-8 reveals that necrosis and inflammation involving hepatocytes are probably the two most common outcomes of druginduced liver injury. There is a huge variation in the degree of necrosis and inflammation that may be seen with any particular drug injury, from coagulative necrosis (usually zonal) with little or no inflammation to mild spotty lobular inflammation with little cell death to fulminant hepatitis with marked inflammation and nonzonal necrosis to patterns that mimic chronic viral hepatitis. Patterns of inflammation can be subdivided into patterns that mimic acute hepatitis, with a lobular predominance of inflammation, patterns that mimic chronic hepatitis (with or without fibrosis) and other more specific patterns, such as granulomatous hepatitis or mononucleosislike sinusoidal infiltrate. These distinctions are useful when formulating a differential diagnosis or in deciding how to further work up the case. It is also important to remember that all of these patterns may have a clinically acute presentation. Acute hepatitis-like injury is dominated by foci of lobular inflammation and spotty necrosis. The degree of severity may vary from a few widely scattered foci or apoptotic hepatocytes to large areas of bridging and confluent necrosis (Figs. 24-1 to 24-5). There is usually portal inflammation and interface hepatitis, sometimes severe, but the majority of the injury is in the lobule. Duct injury may be present, but cholestasis is not observed in the pure acute hepatitic drug injury. Hepatocellular changes can include ballooning and steatosis. There may be evidence of regeneration with the appearance of mitotic figures, widened hepatocyte plates, and hepatocyte rosette formation. Confluent necrosis in zone 3 is not an uncommon finding and may be the result of the toxic injury or extrahepatic causes such as shock. As the injury becomes more severe and the areas of necrosis merge, fulminant hepatitis with massive necrosis may be the result. Trichrome stains can help distinguish between recent parenchymal loss with collapse and parenchymal extinction seen in advanced cirrhosis (see Fig. 24-1C). Unless the injury has been present for longer than clinically recognized (as in some cases of subacute toxic hepatitis) or the patient has some underlying chronic liver disease, it is rare to see more than periportal fibrosis in this pattern of drug-induced liver injury. If canalicular or hepatocellular cholestasis is present along with the acute hepatitislike pattern of injury, then the case is better classified as a mixed cholestatic and hepatocellular type (cholestatic hepatitis), which is discussed subsequently in the section on cholestatic patterns. (Text continued on page 332)
315
316 Table 24-7. Classification of Drug-Induced Liver Injury (DILI) by Pattern of Injury Pattern
Characteristic Features
ALT AST xULN*
AP xULN*
Non-DILI Differential Diagnosis
Drug Examples
Acute (lobular) hepatitis
Lobular-dominant inflammation with or without confluent or bridging necrosis; no cholestasis
++ to ++++
±
Acute viral or autoimmune hepatitis
Isoniazid, sulfonamides, halothane, drugs associated with autoimmune hepatitis
Zonal coagulative necrosis
Zone 3 or 1 coagulative necrosis, usually without significant inflammation
++ to ++++
±
Hypoxic-ischemic injury (zone 3), Herpes and adenovirus usually cause nonzonal necrosis
Acetaminophen (zone 3), carbon tetrachloride (zone 3), ferrous sulfate (zone 1)
Submassive to massive necrosis
Extensive panacinar necrosis, variable inflammation
+++ to ++++
±
Fulminant viral or autoimmune hepatitis
Isoniazid, nitrofurantoin, methyldopa, many others
Chronic (portal) hepatitis
Portal-dominant inflammation, interface hepatitis (also includes mononucleosis pattern), with or without portal-based fibrosis; no cholestasis
+ to +++
±
Chronic viral or autoimmune diseases, early PBC/PSC, mononucleosis-associated hepatitis
Nitrofurantoin, methyldopa, sulfonamides, phenytoin (monopattern), drugs associated with autoimmune hepatitis
Mononucleosis-like hepatitis
Sinusoidal beading
+ to ++++
Variable
Epstein-Barr virus–associated hepatitis
Phenytoin
Granulomatous hepatitis
Inflammation dominated by granulomas (usually non-necrotizing), portal or lobular
+
+ to ++
Sarcoidosis, PBC, fungal and mycobacterial, atypical bacterial infections
Phenytoin
Acute cholestasis (intrahepatic, canalicular)
Hepatocellular and/or canalicular cholestasis in zone 3, may show duct injury but little inflammation
+
+
Sepsis, acute large duct obstruction
Erythromycin, estrogens, androgens, diazepam, diphenylhydantoin
Chronic cholestasis (vanishing bile duct syndrome)
Duct sclerosis and loss, periportal cholate stasis, portal-based fibrosis, copper accumulation
+
+ to ++
PSC
Floxuridine (by hepatic artery infusion)
Chronic cholestasis (PBC-like cholangiodestructive)
Florid duct injury with duct loss, periportal cholate stasis, copper
+
+ to ++
PBC, autoimmune cholangitis, chronic large duct obstruction
Chlorpromazine, amoxicillin-clavulanate, tolbutamide
Mixed hepatocellular-cholestatic (cholestatic hepatitis, hepatocanalicular)
Acute hepatitis pattern plus zone 3 cholestasis, inflammation may be very severe with confluent necrosis
+ to +++
+ to ++
Acute viral hepatitis
Very common DILI pattern: antibiotics, isoniazid, nitrofurantoin, diclofenac
Steatosis, microvesicular
Predominantly microvesicular steatosis, inflammation variable
+ to ++
±
Alcohol, fatty liver of pregnancy
Valproic acid, tetracycline, azathioprine, didanosine, fialuridine
Steatosis, macrovesicular
Predominantly macrovesicular steatosis without significant portal or lobular inflammation, no cholestasis
± to +
± to +
Very common finding in general population, alcohol, obesity, diabetes
Methotrexate, tamoxifen, valproic acid, many organics
Steatohepatitis
Zone 3 ballooning injury, sinusoidal fibrosis, Mallory bodies, variable inflammation and steatosis
± to +
± to +
Common finding in general population, alcohol, obesity, diabetes
Amiodarone, perhexiline maleate, tamoxifen, methotrexate
Necroinflammatory
Cholestatic
Steatotic
Vascular Sinusoidal dilation/peliosis
Sinusoidal alterations with/ without mild lobular inflammation, sinusoidal fibrosis
± to +
+ to ++
Sinusoidal obstruction syndrome/ veno-occlusive disease/BuddChiari syndrome
Occlusion or loss of central veins, thrombosis, with or without central hemorrhage and necrosis
+ to ++
Variable
Hepatoportal sclerosis
Disappearance of portal veins
Nodular regenerative hyperplasia
Diffuse nodular transformation, with or without mild inflammation and sinusoidal fibrosis
Artifactual, acute congestion, bacillary angiomatosis, nearby mass lesions
Androgens, estrogens, glucocorticoids, thioguanine, azathioprine Chemotherapeutic agents, bone marrow transplant prep regimen, certain teas
Arteriohepatic dysplasia
Arsenicals
Variable
+
Collagen-vascular diseases, lymphoproliferative diseases (but perhaps because of DILI)
Azathioprine, thioguanine, mercaptopurine, steroids
Hepatocellular adenoma
Variable
Variable
Sporadic adenomas
Androgens, estrogens, danazol
Hepatocellular carcinoma
Variable
Variable
Sporadic hepatocellular carcinoma
Androgens, estrogens, danazol, Thorotrast
Cholangiocarcinoma
Variable
Variable
Sporadic cholangiocarcinoma
Androgens, Thorotrast, vinyl chloride
Angiosarcoma
Variable
Variable
Sporadic angiosarcoma
Androgens, Thorotrast, vinyl chloride
Type 1 diabetes
Corticosteroids
Neoplasms
Cytoplasmic Alterations and Pigments Glycogenosis
Diffuse hepatocyte swelling with very pale bluish-gray cytoplasm
+ to ++
Ground-glass change
Diffuse homogenization of cell cytoplasm due to induction of smooth endoplasmic reticulum
Cytoplasmic inclusions
Discrete periodic acid–Schiff-positive cytoplasmic inclusions
Gold pigment
Granular black pigment in Kupffer cells
Gold
Thorotrast pigment
Grayish-gold, refractile pigment in Kupffer cells
Thorotrast
Phenobarbital Alpha-1 antitrypsin deficiency
Cyanamid
ALT, alanine aminotransferase; AP, alkaline phosphatase; ASP, aspartate aminotransferase; PBC, primary biliary sclerosis; PSC, primary sclerosing cholangitis; ULN, upper limit of normal. *±: normal to mild elevation (<3 × ULN), + : mild elevation (3–10 × ULN); ++: moderate elevation (10–20 × ULN); +++: marked elevation (20–100 × ULN); ++++: very marked elevation (>100 × ULN). Adapted in part from Zimmerman HJ (eds): Hepatotoxicity: The Adverse Effects of Drugs and Other Chemicals on the Liver. Philadelphia: Lippincott Williams & Wilkins; 1999.
24
317
318 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
PSC-like
End-Stage
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
Drug X
Acarbose Acetaminophen
X
X X
X
Acetohexamide Acetylsalicylic acid (aspirin)
X
Acitretin
X
X
X
X
X
X
X
X
X X
X
X
X
X
X X X X
Ajmaline X
Allopurinol
X
X
X X
Amineptine
X
X
X
X
X
X
X
X
Aminoglutethimide Amiodarone
X
Amitriptyline
X
Amlodipine
X X
X X
X
X
X
X
X
X
X
X
X
X
X X
Amoxicillin-clavulanate
X
X
X
X
X
Ampicillin
X
X
X
Ampicillin-sulbactam X
Amsacrine X
X X
X
X
X
X
X
X
X
X
X
Androgens Aprindine
X
‡
Adriamycin
Anastrozole
X
X
Actinomycin D
Amodiaquine
X
X X
X
X
X
X
X
X
X X
X
X
X
Asparaginase
X X
Atenolol X
Atomoxetine Atorvastatin
X
X
X
X
X X X X
Azacytidine X
Azapropazone
X
X
X X
Azathioprine
X
X
X
X
X X
X
X
X X
Benoxaprofen
X
Benzarone
X
Bromfenac
X
X
Bupropion
X
X
X
X X
X X
X
Busulfan
X
‡
Calcium hopantenate
X
Camphor
X
X
X
X
Candesartan Captopril
X
Carbamazepine
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Carbarsone
X
X
X X
Carbimazole
X X
Carboplatin Carbutamide
X
X
Bacille Calmette-Guérin (BCG)
Carbenicillin
X
X
Azithromycin
Benorylate
X
X
X
X
X X
Carmustine (BCNU)
X
X X
X
Cefadroxil
X
X
Cefazolin
X
X
X
Celecoxib
Cephalexin Chlorambucil
X
X
X
X
X X
X
Table continues on following page.
24
319
320 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
Chloroform
X
X
X
X
Chlorpropamide
X
Cimetidine
X
Cinchophen
X
X
X
X
X
X
X
X
X
X
X X
X
X X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X X
Cholestatic X
X X
X
Mixed
Hepatocellular
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
X
X
Cinnarizine
X X
X X
X
X
‡
X
Citalopram Clarithromycin
X
Clometacin
X
X X
X
X
X
Clopidogrel
X
Clorazepate
X
Corticosteroids
X X
X
X
X X
X
Chlorothiazide
Clozapine
Biochemical†
X
X
Chlorpromazine
Cloxacillin
Tumors
X
Chlorozotocin
Cisplatin
Vascular Injury
X
Chlorotetracycline
Ciprofloxacin
Steatosis
X
Chloropurine
Chlorzoxazone
PSC-like
X
End-Stage
PBC-like
X
Chronic Cholestasis (VBDS)
Chlordiazepoxide
Granulomas
X
Portal Hepatitis
X
Lobular Hepatitis
Chloramphenicol
Zonal Necrosis
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Necroinflammatory
X
X X
X
X X
X
X X
X
X
X
X X
X
Cromolyn
X
X
X
Cyamemazine
X X
Cyanamide X
Cyclofenil
X
X
X
X X
Cyclophosphamide X
Cyclosporin
X
X
X
Cytarabine
X X X
Dantrolene
X
Dapsone
X
X
X X
X X
X
X
X X
X
X
X
X
X
X
X
X
X
X
X X
Daunorubicin
X
X
X
X
Demeclocycline
X
X
X
X
X
X X
Detajmium tartrate
X
X
X
X
X
X
Dextropropoxyphene Diazepam
X
Dichloromethotrexate
X
Diclofenac
X
X
X
X
X X
X
X
X
X
Dicloxacillin
X
Dicoumarol X
Didanosine
X
X
Dihydralazine
X
X
X
X
X X
Diflunisal
X X
Diethylstilbestrol
Dimethylbusulfan
X
‡
Desflurane
X
X X
Dacarbazine
X X
Cysteamine
Diltiazem
X
X
Cyproterone
Desipramine
X
X
Cyproheptadine
Danazol
X
X X
X
X
X
X
X
X X
Table continues on following page.
24
321
322 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
Duloxetine
X
Ebrotidine
X
X
X
X X
X X
X X
X
X
X
X
X
X
X X
Ethacrynic acid
X
X
X
X
X
X X
X
X
Ethambutol X
X X
X
Etodolac
X
X
Etoposide (VP-16)
X
X
Etretinate
X
X
X
X
Ezetimibe
X
X X
X
Fenofibrate
X
X
X X
X
X
Feprazone
X X
Felbamate
X
X
X
§
X
Fialuridine Floxacillin
Cholestatic
Hepatocellular X
X
Estrogens, synthetic
Ferrous sulphate
X
X
X
Erythromycin
X X
X X
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
Tumors
X
Erlotinib
Ethionamide
Vascular Injury
X
X
Enalapril Enflurane
Steatosis
X X
Doxidan
PSC-like
X
PBC-like
X
Chronic Cholestasis (VBDS)
X
End-Stage
Mixed
X
Mixed Cholestatic Hepatitis
Disulfiram
Acute Cholestasis
X
Cholestatic
Granulomas
Disopyramide
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X
X
X X
X
X
X
Floxuridine
X
X X
Fluconazole
X X
Fluoxymesterone
X
Fluphenazine
X
Flurazepam
X X
X
X
X X
X X
X
X
X
X X
Gemtuzumab
X
Gliclazide
X
Glyburide (glibenclamide)
X
X
Gold
X
X
X
X
X
Gemcitabine
X X
X
X
X
X X X
X
X
X
X
X
X
Griseofulvin Haloperidol Halothane
X
Hycanthone
X
X
X
X
X
X X
X
X X
X
X X
X
Hydrochlorothiazide
X
X
X
X
X
X
X
X
X
Hydroxyprogesterone
X
Hydroxyurea
X X
Ibufenac X
Ibuprofen
X
X
X X X
X
X
X
X
Idoxuridine Imatinib mesylate
X
Imipramine
X
X
X
X X
X X
Indicine X
Indinavir Indomethacin
X
X
Infliximab
X
X
X X
X
X X
X X
X
X
X
Hydralazine
Interferon alpha
X X
X
Flutamide Gatifloxacin
X
X
X
Fluoxetine
Fluroxene
X
X
X
X X
X
X X
X
X Table continues on following page.
24
323
324 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Interleukin-2
X
X
X
X
X X
Iodipamide meglumine
X
X
X X
Ipilimumab
X
X X
Iprindole
X X
Iproclozide X
X
X
X
X
Irbesartan
X
X
Isocarboxazid
X
X
Iproniazid
Isoflurane
X
Isoniazid
X
X X
X
X
X
X
X
X
X
X
X
X
Lamotrigine
X
X
X
X
X
X
X
X
X
X
X X
X
X
X
Loratadine Losartan
X
X
Lergotrile
Lisinopril
X
X
X X
Labetalol
X
X
Ketoprofen
Levofloxacin
X
X
Itraconazole Ketoconazole
Cholestatic
X
X
Interleukin-6
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Steatosis
X
Interferon beta
Iodoform
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X X X X
X
Lovastatin
X
X
X X
Loxapine
X
X
Medroxyprogesterone
X X
Mefloquine X
Meglumine antimonate X
Mercaptopurine Mesalamine (mesalazine)
X
§
X
X X
Metformin
X
X
X
X
X
Methotrexate
X
X
X
X
X
X
X X
X
X
X
X
X X
X
X
X
X
X
Methylthiouracil
X
X
X X
X
X
X
X
X
Mirtazapine
X
X
X X
X
Monomethylformamide
X
X
Naproxen
X
X
X
X
Mitomycin C
Nevirapine
X
X
X
X
X
X X
Nefazodone
X
X
X
Minocycline
Niacin
X
X X
X
Mithramycin
X
X
X
Methyltestosterone
Metoprolol
X
X
Methyl salicylate Methyldopa
X
X
X
Methimazole
X
X X
Methandrostenolone
X
X
X
Mestranol
Methoxyflurane
X
X
X
X
X
X
X
X
X
X
Nimesulide
X
X
Nitrofurantoin
X
X
X
Nomifensine
X
Norethindrone
X
X
X
X
X
X
X
X X
X
X
X
X
X
X
X
X
X
X
Nifedipine
X
X
X
X X
X
X
X
X
X X
Table continues on following page.
24
325
326 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
X
Granulomas
X
Portal Hepatitis
Lobular Hepatitis
Norfloxacin
Zonal Necrosis
Necroinflammatory
X
Novobiocin
X
X
Ofloxacin
X
X
X
X
X
Oxacillin
X
Oxaprozin
X
X
X
X
X
X
Oxymetholone
X
X
X
X
X
X
X
X X
Oxytetracycline Papaverine
X
X
X
X
X
X
X
X
X X
Penicillamine X
Penicillin
X
X
X
X
Pentamidine X
X
X
X
X
X
X
X
X
Phenazone Phenazopyridine
X
X
Paroxetine
Perhexiline maleate
X
X
X
Para-aminosalicylic acid
Pemoline
X
X
Oxyphenbutazone Oxyphenisatin
X
X X
Phenelzine Phenindione
X
Phenobarbital
X
Phenprocoumon
X
X
X
X X X
X
X
X
X
X
X
X
X
X X
Phenylbutazone
X
X
X
X
X
Phenytoin
X
X
X
X
X
Pioglitazone
X
X
Piroxicam
X
X
X
X X
X
X X
X
X
X
X X
Prajmalium
X
X
X
Pravastatin Probenecid
X
Procainamide
X
X
X X
X
X X
Prochlorperazine
X
X X
X
X
X
X
Propafenone X
Pyrazinamide
X
X
X
X
X X
X
X X
X
X
Quinethazone X
X
X
X
X
X
Quinine
X
Raloxifene X
Ramipril X
Ranitidine
X
X
X
X
X
X
X
X
Repaglinide X
X
X
X
X
X X
Rofecoxib X
Rosiglitazone X X
X
X
Sibutramine
X
X
X
X
X X
X
X
X
X X
Sevoflurane
X X
X
Ritonavir
Rosuvastatin
X
X
Risperidone
X X
X
Riluzole
Roxithromycin
X
X
Practolol
Rifampin
X
X
Pizotifen
Quinidine
X
X
Pirprofen
Propylthiouracil
X
X X X
Table continues on following page.
24
327
328 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Streptozotocin
X
Sulfadiazine
X
X
Sulfadoxine-pyrimethamine
X
Sulfamethizole
X
Sulfamethoxazole
X
Sulfasalazine
X
X
Sulindac
X
X
X
X
X
X
X
X
X
X X
X
X
X
X
X X X
X
X
X
X
X
X
X
X
X
X X
X
Tacrine
X
X
X X
Tamoxifen X
X
X
X X
Terbinafine Terfenadine
X
Testosterone
X
X
X
X
X
X X
X
X
X
X
X
X
X
X X
X X
Tetracycline X
X
X
X
X
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
Sinusoidal Dilation
Peliosis
Budd-Chiari
VOD/SOS
Steatohepatitis
Macrovesicular Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
PSC-like
X
Sulpiride
Thioguanine
Vascular Injury
X
Suloctidil
Thiabendazole
Steatosis
X
Sulfadimethoxine
Thalidomide
PBC-like
X
Streptokinase
Telithromycin
End-Stage
X
Stavudine
Tacrolimus
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
X
Cholestatic
Acute Cholestasis
X
Granulomas
Portal Hepatitis
Simvastatin
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X
X
X X
X
X
X
X
X X
X
X
X
X
X
Thiopental X
Thioridazine X
Thiotepa
X‡
Thorium dioxide (Thorotrast)
X
Ticarcillin-clavulanate
X
X
X
X
X X
X X
X
X
X
X
X
X
X
Tocainide
X
X
X
X
Tolbutamide
X
X
X
X
X
X
X X
X X
Tolcapone
X X
Tolmetin Toloxatone
X
X
Tiopronin
Tolazamide
X X
Ticlopidine Ticrynafen
X
X
X
Total parenteral nutrition
X
Tranylcypromine
X X
Trazodone
X
X
X
X
X X
X
X
X
X
Triazolam
X
X
Trichlormethiazide Trifluoperazine
X
Trimethobenzamide
X
X
Trimethoprim
X
X
X
Trimethoprim-sulfamethoxazole
X
X
X
X
X
X
Trovafloxacin
X
Urethane
X
Valproic acid
X
Venlafaxine
X
X
X
X
X X
X
X X X
X
X
X
X X
X
X X
X
X X
X
Troleandomycin
Verapamil
X
X
Tripelennamine Troglitazone
X
X
X
X
X
Table continues on following page.
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329
330 Table 24-8. Index of Drugs and Herbal Agents Associated with Hepatotoxicity*—Cont.
X
Vitamin A X
Warfarin
X
X X
X
X
X
X
X
Xenylamine X
Ximelagatran
Cholestatic
Mixed
Hepatocellular
Biochemical†
Angiosarcoma
Cholangiocarcinoma
Hepatic Carcinoma
Hepatitis Adenoma
Tumors
NRH
X
Sinusoidal Dilation
Budd-Chiari
X‡
Peliosis
VOD/SOS
Vincristine
Vascular Injury
Steatohepatitis
Macrovesicular Steatosis
Steatosis
Microvesicular Steatosis
Fulminant Hepatitis
Cirrhosis
End-Stage
PSC-like
PBC-like
Chronic Cholestasis (VBDS)
Mixed Cholestatic Hepatitis
Cholestatic
Acute Cholestasis
Granulomas
Portal Hepatitis
Lobular Hepatitis
Zonal Necrosis
Necroinflammatory
X
X
X X
Zafirlukast
X X
Zidovudine
X
X
Zimelidine
X
Zoxazolamine
X
Herbal Agent X
Barakol Black cohosh
X
X
X
X X
Bush tea (pyrrolizidine alkaloids) X
Cascara sagrada Chaparral
X
X
X
X
X
Chaso/Onshido
X
X
X X
X
X
X
X
Green-lipped mussel (Seatone) Jin bu huan
X
X
Glycyrrhizin Greater celandine
X
X
Comfrey Germander (Teucrium)
X
X
X
X
X
X
Kava kava Ma huang
X
X
X
X X
Margosa oil
X
Mate tea X
Mineral oil Oil of cloves
X
Pennyroyal oil
X
X X X
Pentanoic acid X
Polyvinyl pyrrolidone
X
Prostata X
Senna X
Skullcap Syo-saiko-to
X
Tannic acid
X
Usnic acid
X
X
X
X X
X
NRH, nodular regenerative hyperplasia; PBC, primary biliary cirrhosis; PSC, primary sclerosing cholangitis; VBDS, vanishing bile duct syndrome; VOD/SOS, veno-occlusive disease/sinusoidal obstruction syndrome. *The patterns of pathology and biochemistry presented in this table are meant to be general guides and not absolute criteria. † Biochemical injury as defined by the ratio of alanine aminotransferase to alkaline phosphatase as described in the text. ‡ Only in combination with other agents or radiotherapy. § Predominantly zone 1 necrosis. Data were compiled from multiple sources, including the primary literature, as well as Zimmerman HJ (eds): Hepatotoxicity: The Adverse Effects of Drugs and Other Chemicals on the Liver. Philadelphia: Lippincott Williams & Wilkins; 1999; Norris W, Paredes AH, Lewis JH: Drug-induced liver injury in 2007. Curr Opin Gastroenterol. 2008;24:287–297; Snover DC: Drug-induced liver disease. In: Snover DC (ed): Biopsy Diagnosis of Liver Disease, Baltimore, MD: Williams & Wilkins; 1992, pp. 164–177; Lewis JH, Ahmed M, Shobassy A, et al: Drug-induced liver disease. Curr Opin Gastroenterol. 2006;22:223–233; Lazerow SK, Abdi MS, Lewis JH: Drug-induced liver disease 2004. Curr Opin Gastroenterol. 2005;21:283–292; and Arundel C, Lewis JH: Drug-induced liver disease in 2006. Curr Opin Gastroenterol. 2007;23:244–254.
24
331
Practical Hepatic Pathology
A
B Figure 24-1. Nitrofurantoin toxicity—acute fulminant hepatitis. Nitrofurantoin has been associated with both acute and chronic liver disease. The biochemical presentation varies from pure hepatocellular to cholestatic, and most of the reported cases are in women and in older individuals. Toxicity may not develop until the patient has been on the drug for several years, and yet the patient may still present in fulminant hepatic failure. The histopathology mainly shows changes of hepatitis and the distribution, and severity may mimic both acute and chronic viral hepatitis. Severe fibrosis and cirrhosis may be present at the time of biopsy. This patient presented with acute hepatitis and jaundice. (A) The biopsy shows lobular inflammation associated with ballooning injury of hepatocytes. There is extensive hepatocyte drop-out in zone 3 in this portion of the biopsy, whereas other areas show panacinar necrosis. (B) The infiltrate is mainly lymphocytic with scattered eosinophils and plasma cells. Hepatocellular rosettes are present. Canalicular cholestasis is not seen. (C) A Masson stain in an area of panacinar necrosis shows relatively preserved portal areas with collapse of intervening parenchyma. No hepatocytes remain in this portion of the biopsy, but there is a ductular reaction and persistent inflammation (Masson trichrome).
C
Drugs may also cause a pattern of injury that may be indistinguishable from chronic viral or autoimmune hepatitis on histologic grounds alone (Figs. 24-6 and 24-7). In fact, many of the drugs that can cause the acute or lobular hepatitis pattern may also cause one resembling chronic hepatitis. Some common agents associated with the chronic hepatitis-like pattern include nitrofurantoin, isoniazid, and the sulfonamides (see Table 24-8). In these biopsies, there is generally portaldominant inflammation with interface hepatitis associated with a mild to moderate degree of spotty lobular inflammation. Apoptotic hepatocytes as well as other evidence of injury such as ballooning degeneration and steatosis may be seen. As with the acute hepatitis-like injury, if canalicular or hepatocellular cholestasis is present, these cases should be classified with the mixed cholestatic and hepatocellular type for the purposes of differential diagnosis. This pattern of injury tends to have lower transaminase elevations than the acute hepatitis forms and may go undetected for a long time. Cirrhosis may develop, as in the case of nitrofurantoin toxicity shown in Figure 24-7. In such cases, other causes of cirrhosis should be excluded histologically and clinically. Drugs that cause chronic hepatitis patterns may be further subdivided by whether or not they are associated with features of autoimmune hepatitis.54 A number of drugs, including nitrofurantoin55 (see Figs. 24-1, 24-6, and 24-7), methyldopa,56,57 and minocycline,58 induce an autoimmune hepatitis that is clinically similar to sporadic type I autoimmune hepatitis and termed drug-induced chronic hepatitis, type 332
I. Patients frequently have circulating antinuclear and/or anti–smooth muscle antibodies, high gamma globulin levels, and plasma cell–rich infiltrates on liver biopsy. Like the sporadic form of autoimmune hepatitis, there is a female predominance, and the onset may be acute or chronic. A second group of drugs is associated with autoantibodies directed against microsomal proteins such as isoforms of cytochrome P450, similar to type II autoimmune hepatitis. These drugs are categorized as inducers of drug-induced chronic hepatitis type II and include dihydralazine (anti-CYP1A2),59 ticrynafen (anti-CYP2C9),60 and halo thane (anticarboxylesterase and anti–protein disulfide isomerase).61 A third group includes drugs such as sulfonamide, lisinopril, and trazodone that have not yet been associated with an autoantibody but may show chronic hepatitis-like histology. Phenytoin, dapsone, and several other agents have been associated with a pseudomononucleosis type of inflammatory pattern.62,63 There is sinusoidal beading present, and both phenytoin and dapsone may also induce granulomas and eosinophils. Infection by Epstein-Barr virus should be excluded by the usual means. A large number of drugs have been associated with granulomatous inflammation (see Table 24-8). The presence of microgranulomas (small collections of 3 to 10 epithelioid macrophages) in the hepatic parenchyma is a common finding in many types of chronic liver disease. They should not, by themselves, lead to a diagnosis of granulomatous h epatitis, drug-induced or otherwise. Larger epithelioid granulomas, particularly
Liver Injury Due to Drugs and Herbal Agents
24
A
A
B
B Figure 24-3. Lamotrigine toxicity. Lamotrigine is an antiepileptic drug that has recently been associated with an acute hepatitic type of hepatotoxicity. (A) This biopsy from a patient with lamotrigine hepatitis shows several large foci of lobular inflammation associated with hepatocellular apoptosis. The inflammation is lymphohistiocytic with eosinophils. (B) The portal areas are filled by a lymphocytic infiltrate with numerous eosinophils. Interface hepatitis is present, and several apoptotic hepatocytes can be seen at the edges of the portal area. The ducts are relatively unaffected by the infiltrate. There was no cholestasis visible in the biopsy.
C Figure 24-2. Isoniazid hepatitis. Isoniazid causes hepatocellular injury with jaundice in about 1% of patients. The incidence increases with age and alcohol use. Patients on more than one antituberculous agent may also be at risk for hepatotoxicity. The histologic pattern of injury varies from acute hepatitis to cholestatic hepatitis. (A) This example of isoniazid injury shows diffuse lymphocytic inflammation involving portal areas and hepatic parenchyma with hepatocyte drop-out. Scattered eosinophils are present, but plasma cells are only rare. (B) At high magnification, acidophil bodies are readily identified. There is wide variation in hepatocyte cell size, consistent with regeneration. (C) In this case, there is mild duct injury. The ductal epithelial cells show reactive changes, with nuclear variation and crowding. There is also a prominent ductular reaction with a neutrophilic infiltrate. No canalicular or hepatocellular cholestasis is seen in this case despite significant jaundice.
Figure 24-4. Ciprofloxacin hepatitis. Ciprofloxacin has been associated with both hepatitic and cholestatic jaundice. In this case, there is both portal and lobular inflammation, with eosinophils and plasma cells in the infiltrate. There was no cholestasis in the biopsy. 333
Practical Hepatic Pathology
A
A
B
Figure 24-5. Herbal-associated hepatotoxicity. Hepatotoxicity due to herbal nutritional supplements has been the subject of a number of case reports and small case series. Pathology ranging from fulminant hepatitis to cholestasis to sinusoidal obstruction syndrome has been observed. (A) This biopsy was obtained from a patient with acute hepatitis due to a green tea extract. There is prominent necrosis in zone 3 associated with a predominantly lymphocytic infiltrate. There is bridging necrosis between the central vein and the adjacent portal area. (B) This biopsy was obtained during an episode of jaundice due to chaparral (beechwood creosote). There is a predominantly lobular hepatitis without cholestasis. The moderate steatosis present was most probably related to the patient’s obesity.
B
A
B
C
D
Figure 24-6. Nitrofurantoin toxicity–chronic hepatitis pattern. This case presented with moderate elevations of transaminases and a normal bilirubin. (A) The distribution of inflammation observed at low power is mainly portal and periportal, mimicking chronic viral hepatitis. The lobular inflammation is relatively mild compared with the acute hepatitis presentation in Figure 24-1. (B) The portal areas show lymphoplasmacytic infiltrates with scattered eosinophils. There is interface hepatitis, and the duct is uninjured. (C) A feature not consistent with chronic viral hepatitis is the presence of central necrosis. Similar to the acute hepatitis presentation, there is accentuation of inflammation and necrosis in zone 3. (D) Focally, bridging necrosis is present, here connecting a central vein region with a portal area. This is another feature of severity that would be unusual in chronic viral hepatitis but would be more common in autoimmune hepatitis. 334
Liver Injury Due to Drugs and Herbal Agents
A
B
C Figure 24-7. Advanced liver disease due to nitrofurantoin. Patients who develop nitrofurantoin toxicity may develop advanced fibrotic liver disease. This biopsy was taken about two months after the acute presentation at a time when the transaminases were only mildly elevated. (A) There is clear evidence of bridging fibrosis and nodule formation consistent with at least incomplete cirrhosis. Mild to moderate lymphocytic inflammation is present with focal interface hepatitis (Masson trichrome). (B) Some portal areas showed cholate stasis of the periportal hepatocytes, here associated with the absence of the bile duct. (C) Copper accumulation was seen in some of the periportal hepatocytes (rhodanine). The chronic cholestatic features in this case may be due as much to the advanced stage of the liver disease as to drug toxicity.
when present in significant numbers, may be a clue to drug-induced injury, particularly when sarcoidosis and infections have been excluded. In McMaster’s series of 95 cases of granulomatous hepatitis, about 30% were attributed to drugs.64 A wide variety of drugs were incriminated, including antihypertensives, anticonvulsants, antirheumatics, antimicrobials, antiarrhythmics, antineoplastics, anxiolytics, and contraceptives. Other authors have noted a lower incidence related to drugs, anywhere from 1% to 10%.65–68 The drugs for which granulomas are a common component of the injury include allopurinol, carbamazepine, copper sulfate, diphenylhydantoin, phenylbutazone, phenytoin, quinidine, and quinine.69 Granulomas in drug injury may be parenchymal, portal, or periductal, mimicking the florid duct lesion of primary biliary cirrhosis. Fibrin-ring granulomas have been associated with allopurinol.70 Eosinophils may be seen in and around drug-induced granulomas, and granulomas may be an indicator of hypersensitivity reactions. The death of hepatocytes usually takes one of two forms, apoptosis and necrosis.71,72 Apoptosis, or single cell death, is observed in most drug-induced injuries to some degree. Apoptotic hepatocytes are recognized as small, shrunken, hypereosinophic bodies with or without a condensed, fragmented nucleus. They may be found associated with clusters of inflammatory cells, adjacent to larger areas of necrosis or occasionally as free bodies in the sinusoids. In the context of druginduced injury, apoptosis may result from selective injury to organelles that triggers the death pathway or by initiation of apoptosis by immune cells during a hypersensitivity reaction. There is usually no clear zonal distribution of apoptosis in drug injury. Idiosyncratic drug injuries are most often associated with apoptotic cell death rather than necrosis. However, in severe cases of necroinflammatory drug injury, hepatocellular cell death may occur so rapidly and completely that it is no longer possible to distinguish the actual mechanism of cell death. In contrast to apoptosis, necrosis occurs when a cell receives massive injury in a short period of time. This injury can result from an environmental cause, such as sudden, severe hypoxia, thermal injury, or massive injury from a drug or toxin. Cell membranes and organelles are injured indiscriminately, and the cell rapidly loses all internal integrity. Because the lobular architecture of the liver defines a hepatocyte’s access to blood flow and oxygen as well as the levels of detoxifying enzymes, necrosis frequently occurs in a zonal distribution. Intrinsic hepatotoxins, both direct and indirect, are often incriminated when zonal necrosis is the dominant form of injury. Zonal necrosis usually involves either zone 3 or zone 1. Zone 2 necrosis has been produced in experimental model systems of toxicity but is very rare in human drug injury. Idiosyncratic toxins may also produce zonal injury, perhaps as a result of increased susceptibility of cells in particular zones or from particularly intense perivenular or periportal inflammatory infiltrates. Zone 3 necrosis is the most common form of zonal necrosis and is the characteristic form of toxicity due to acetaminophen and carbon tetrachloride. In the case of both of these agents, there is little inflammation except for macrophages and neutrophils that have been drawn to the area secondarily. Early on after the initiation of the injury, a biopsy will show sheets of hepatocyte ghosts in a zone 3 distribution (Fig. 24-8). Hemorrhage can be seen as the sinusoidal structure breaks down, and steatosis may be seen in the non-necrotic liver. The entire acinus may be involved in severe injuries. If the patient survives the initial toxic insult, the dead hepatocytes will be phagocytized and removed, leaving a zone of collapsed reticulin. With sufficient time, the liver can regenerate to the point where the architecture is essentially normal. Zone 1 coagulative necrosis is rarer but has been associated with poisoning by direct intrinsic hepatotoxins such as phosphorus,73,74 ferrous sulfate,75 and concentrated acetic acid.76 Finally, it should be remembered that zonal necrosis (particularly zone 3 necrosis) may be observed in hepatitic and vascular patterns of drug injury.
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Figure 24-8. Zonal necrosis due to acetaminophen. Acetaminophen causes a distinctive pattern of coagulative, zonal necrosis with minimal inflammation consistent with its intrinsic toxicity. The degree of toxicity increases with increased dose, increased acetaminophen blood levels, increased cytochrome CYP2E1 activity, decreased glutathione stores, increased alcohol consumption, fasting, and obesity. (A) There is coagulative necrosis of hepatocytes involving about 50% of the parenchyma. (B) At the interface between the viable and necrotic liver, there is steatosis and ballooning of hepatocytes. (C) In the viable areas of the liver, isolated apoptotic hepatocytes can be seen, along with mitotic figures. (D) In this biopsy from a case of acetaminophen toxicity in a chronic alcoholic, the lipid vacuoles in the steatotic hepatocytes fuse to form large irregular lipid lakes. (Courtesy of Dr. Linda Ferrell, University of California, San Francisco)
Cholestatic Patterns Cholestatic presentations of liver injury are not as common as hepatitic presentations, accounting for only 17% of cases in a large series from Denmark.31 Like the hepatitic patterns of drug-induced liver injury, the cholestatic patterns may be subdivided into several forms that mimic acute and chronic nondrug cholestatic liver disease. On the acute side are the patterns of pure intrahepatic cholestasis and mixed hepatocellular-cholestatic injury or cholestatic hepatitis (see Table 24-8). Acute intrahepatic cholestasis is characterized mainly by the accumulation of bile within canaliculi (canalicular cholestasis) and hepatocytes (hepatocellular cholestasis) (Figs. 24-9 to 24-11). Within hepatocytes, bile may be difficult to distinguish from other hepatocellular pigments such as lipofuscin and iron. Bile appears as variably sized rounded inclusions that are pale green to greenish brown in color. Iron stains can be very helpful by both excluding the possibility of iron and allowing the cytoplasmic pigments to be more clearly seen (see Fig. 24-9D). The low background counterstain used in rhodanine stains is also useful for visualizing intracellular bile (see Fig. 24-10C). Ballooning hepatocellular injury may accompany the bile stasis. Cholestasis is most prominent 336
in zone 3; other processes such as sepsis and acute large duct obstruction that may also present with isolated zone 3 cholestasis should also be excluded. In the most pure forms of acute intrahepatic cholestasis, such as the cholestasis from androgenic or contraceptive steroids, there is little or no inflammation. In most cases of drug-induced cholestasis, both hepatocellular and canalicular cholestasis are present, although the sex steroids notably produce only canalicular cholestasis. A mild degree of lobular and/or portal inflammation as well as duct injury may also be present. It is much rarer to see bile plugs in interlobular ducts or cholangioles in drug-induced cholestasis although benoxaprofen has been reported to cause both.5 As the degree of inflammation associated with the intrahepatic cholestasis increases, the cases are better classified as mixed hepatocellular-cholestatic injury (cholestatic hepatitis). The reason for making this distinction has more to do with the pathologic differential diagnosis than with distinctive patterns of drug injury, because many drugs that cause cholestatic hepatitis are also associated with blander forms of cholestasis or with the acute hepatitis pattern (see Tables 24-7 and 24-8). This mixed pattern of injury is a common pattern of drug-induced liver
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E Figure 24-9. Cholestatic injury due to amoxicillin-clavulanate. Patients who develop toxicity to amoxicillin-clavulanate usually present after they have completed their course of therapy. The injury is usually cholestatic and is recognized by the development of jaundice 1 to 9 weeks after stopping the drug. Histologically, all forms of cholestatic injury have been reported, from pure intrahepatic cholestasis to mixed hepatitic/cholestatic injury to vanishing bile duct syndrome. (A) Pure intrahepatic cholestasis injury shows little inflammation—usually a sparse portal infiltrate and very rare foci of spotty necrosis, leading to a nearly normal appearance at low magnification. (B) Careful examination reveals canalicular cholestasis (arrow), occasional enlarged hepatocytes with clearish, microvacuolated cytoplasm and small clusters of pigmented macrophages. (C) This biopsy from a case with mixed injury shows numerous foci of spotty lobular inflammation alongside canalicular and hepatocellular cholestasis. (D) Iron stains are helpful in distinguishing pigments in the liver. Bile plugs may be easier to see in an iron stain than in a standard hematoxylin and eosin because the brownish-green bile pigment contrasts well with the pale pink of the background in an iron stain. (E) Duct injury is frequently seen in cases of amoxicillin-clavulanate injury. In this case it took the form of primary biliary cirrhosis– like florid duct lesions. The ductal epithelium is extensively infiltrated and shows a hyperplastic response. There is a prominent eosinophilic infiltrate and cholate-stasis changes in the periportal hepatocytes. 337
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Figure 24-10. Azithromycin toxicity. Intrahepatic cholestasis and cholestatic hepatitis are typical patterns of injury with the macrolide antibiotics. Injury has been more often reported with erythromycin than with the other members of the drug family. This case demonstrated acute intrahepatic cholestasis with loss of the small bile ducts. (A) There is zone 3 cholestasis with accumulation of bile pigment mainly in hepatocytes, although canalicular cholestasis is also present. This accumulation is associated with mild hepatocyte swelling and occasional hepatocyte apoptosis. There is almost no inflammatory infiltrate. (B) Most of the small portal areas lacked a visible bile duct, but there was no evidence of periportal cholate-stasis. (C) The copper stain was negative for copper accumulation, but the zone 3 bile stasis was evident as a greenish discoloration (upper left) (rhodanine stain). 338
Figure 24-11. Cholestatic injury with duloxetine. Duloxetine has only recently been associated with hepatotoxicity with a reported case of fulminant hepatic failure. Here are two examples of cholestatic injury judged to be due to duloxetine. (A) The first case shows acute intrahepatic cholestasis with very little inflammation. There is no hepatocellular drop-out, but scattered pigmented macrophages are seen in the sinusoids. There is only mild portal inflammation without interface hepatitis. (B) Under high magnification, canalicular and hepatocellular cholestasis are identified, mainly around the central veins. (C) A separate case shows mixed hepatocellular and cholestatic injury, with lobular inflammation, hepatocyte drop-out and canalicular cholestasis. There is prominent Kupffer cell hypertrophy in the sinuses (pale cells between hepatocyte cords).
Liver Injury Due to Drugs and Herbal Agents injury, but it is unusual outside that context. Lewis and Zimmerman further divided this pattern into three: mixed-hepatocellular, mixed hepatocanalicular, and mixed cholestatic, depending on whether hepatitic or cholestatic features predominated.77 All cases show some degree of hepatocellular injury, with inflammation of the lobules and portal areas along with zone 3 predominant canalicular and hepatocellular cholestasis (Figs. 24-12 to 24-14; see Figs. 24-9 and 24-11). The inflammatory pattern may mimic either the acute or chronic hepatitis-like patterns described earlier, although it is more common to see the acute hepatitis pattern. Duct injury may be present, and with some drugs such as amoxicillin-clavulanate, chlorpromazine, and trimethoprim-sulfamethoxazole, patients may develop a vanishing bile duct syndrome.78–80 Drugs may cause a variety of injuries that can be grouped together under the general pattern of chronic cholestasis. These include patterns of ductal paucity, often termed vanishing bile duct syndrome, and injuries that mimic the more specific lesions of primary sclerosing cholangitis
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C B Figure 24-12. Fluvastatin-related cholestatic hepatitis. Statins are only very rarely causes of significant hepatic injury. Because statins are used in a patient population (hypercholesterolemics) that is at risk for fatty liver disease, these patients may have mildly elevated transaminase levels unrelated to drug therapy. This case of fluvastatin toxicity demonstrated mild mixed hepatocellular and cholestatic injury on biopsy. (A) Examination of zone 3 shows canalicular cholestasis associated with mild lobular inflammation and hepatocellular apoptosis. There was also mild duct injury. (B) A PAS stain performed with diastase digestion shows numerous small clusters of PAS-positive macrophages in zone 3.
Figure 24-13. Trimethoprim-sulfamethoxazole–related injury. The combination drug trimethoprim-sulfamethoxazole causes a wide range of injury from nearly pure intrahepatic cholestasis to acute hepatitis, with cholestatic presentations being more common. This case shows mixed hepatocellular and cholestatic injury on a background of mild fatty liver disease, probably related to obesity. (A) The inflammatory infiltrate is mild in intensity and present mainly in the portal areas. There is interface hepatitis as well as ductular reaction, both of which obscure the limiting plate. (B) The portal infiltrate is mainly lymphocytes, with increased numbers of eosinophils. (C) Canalicular cholestasis is present throughout the lobule but is most visible in zone 3. 339
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Figure 24-14. Atomoxetine toxicity. Atomoxetine is a recently developed norepinephrine reuptake inhibitor used to treat attention-deficit hyperactivity disorder. Several case reports have linked it with hepatotoxicity. This biopsy was obtained in the midst of the biochemically hepatitic presentation associated with jaundice. The histologic pattern of injury is a cholestatic hepatitis with the hepatitic component being the more prominent one. (A) At low magnification, there is both portal and lobular inflammation, with evidence of hepatocellular injury in the form of ballooning and hepatocyte rosette formation. (B) There is a mild to moderate portal inflammatory infiltrate with interface hepatitis and scattered eosinophils. This portal area had no visible duct, but ducts were present in most other portal tracts. (C) In zone 3 there is evidence of focal hepatocyte drop-out and dilated canaliculi with pale bile accumulation. (D) The canalicular cholestasis is more apparent on the iron stain, where it is seen as pale greenish-pink plugs in canaliculi.
(biliary sclerosis) and primary biliary cirrhosis.77,81 Drugs and other toxins may directly injure the cholangiocytes,82 or the ducts may be destroyed secondarily by inflammation or ischemia. Duct injury by itself should not be taken as the characteristic lesion of chronic cholestasis, because it may be observed in the hepatitic and cholestatic patterns discussed earlier. It is more important to evaluate all of the portal areas systematically and assess the status of the main duct—intact, injured, inflamed, or missing. Cytokeratin 19 stains may be useful in identifying duct remnants obscured by inflammation. Ductular reaction may be present with duct loss, but it is not a specific finding. It is better to look for evidence of cholate stasis (Fig. 24-15; see Fig. 24-9E), the microvacuolar change in periportal hepatocytes that is the result of bile salt accumulation. Copper stains can also be useful markers in the evaluation of chronic cholestasis, although they may also be positive in advanced stage liver disease from all causes. Fibrosis can develop secondarily as in other chronic cholestatic liver diseases. The primary sclerosing cholangitis–like injury of biliary sclerosis is a relatively unusual pattern of chronic cholestatic drug injury, associated mainly with hepatic arterial infusion of floxuridine83,84 as well as with the treatment of echinococcal 340
cysts with scolicides.85 The injury has been attributed to arterial damage by the agents rather than direct injury to the bile ducts. Ludwig86 has therefore termed this change ischemic cholangiopathy.
Steatotic Patterns The steatotic patterns of drug-induced liver injury include both microvesicular and macrovesicular steatosis as well as steatohepatitis (see Table 24-8). Macrovesicular steatosis may be observed as one component of another pattern of injury, such as zonal necrosis, as shown in the acetaminophen toxicity example of Figure 24-8. In such cases, the injury should be classified as the other pattern rather than as a steatotic pattern. Nonalcoholic fatty liver disease (NAFLD) and its alcohol-induced counterpart are the main etiologic alternatives for drug- or toxin-induced steatosis. As the prevalence of NAFLD rises in the general population, ascribing steatosis to a direct drug effect becomes more and more difficult. Nevertheless, there are some drugs, such as corticosteroids and methotrexate, that are clearly associated with steatosis. Like NAFLD, macrovesicular steatosis is often accompanied by a mild lobular or portal inflammatory infiltrate. The presence of other features, such as
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Figure 24-15. Chronic cholestatic hepatitis due to cefuroxime. Cephalosporins only rarely cause hepatic injury, and when they do, it is often a cholestatic jaundice, as is the case in this example of injury due to cefuroxime. Overall the biopsy shows changes reminiscent of chronic autoimmune hepatitis, but with some notable and unusual features. (A) The portal areas show a relatively mild lymphocytic infiltrate with prominent ductular reaction and cholate stasis (pseudoxanthomatous change) in the periportal hepatocytes. The ducts were intact although some show injury. (B) The chronic cholestatic changes are corroborated by a positive copper stain (rhodanine). (C) In addition to the portal inflammation, there is zone 3 necrosis, which is associated with a prominent plasma cell infiltrate. (D) A Masson trichrome stain shows areas of bridging fibrosis involving portal areas and central veins.
c holestasis or severe necroinflammatory changes, would suggest a mixed pattern of injury in which the steatosis may not even be related to the suspect agent (Fig. 24-16). Features of ballooning hepatocellular injury, perisinusoidal fibrosis, and Mallory body formation are characteristic of steatohepatitis. Drug-induced steatohepatitis has been attributed to a number of agents. Amiodarone and perhexiline cause a form of steatohepatitis associated with phospholipidosis (Fig. 24-17), which is an accumulation of lipid membrane material within the lysosomes of macrophages, not unlike a storage disease. Phospholipidosis may be generalized and affect other sites than the liver.87–89 Other drugs, such as methotrexate, tamoxifen, and the corticosteroids (Fig. 24-18), may exacerbate preexisting steatohepatitis or may develop a synergistic toxic effect with alcohol. The protease inhibitor class of antiretrovirals has been associated with a systemic syndrome of dyslipidemia, fat maldistribution, and insulin resistance that may secondarily cause steatosis and steatohepatitis.90 As with nonalcoholic and alcoholic steatohepatitis, drug-induced macrovesicular steatosis and steatohepatitis are chronic, generally lowgrade injuries, but at least in the case of steatohepatitis, serious liver disease in the form of cirrhosis may develop subclinically.91,92
Microvesicular steatosis is a more serious lesion that often presents with hepatomegaly and hepatic failure. It is almost always the result of a drug or toxic injury, frequently involving the mitochondria and leading to lactic acidosis. Histologically, microvesicular steatosis is characterized by a diffuse foamy change in the hepatocytes (Fig. 24-19). Mild inflammation, intrahepatic cholestasis, and individual hepatocyte apoptosis may be seen, but usually there is no massive necrosis as seen in severe acute hepatitic injury, which may present clinically in a similar fashion. A number of drugs have been associated with microvesicular steatosis and hepatic failure, most notably acetylsalicylic acid (Reye syndrome),93 valproic acid,94 the tetracylines,95 and some nucleoside analogs.96,97 The injury may continue to progress, even after the patient has stopped taking the drug. In the case of fialuridine, a nucleoside analog, hepatic failure developed in some patients weeks after they had stopped the drug.98,99 The mechanism of injury in microvesicular steatosis has been linked to the uncoupling of oxidative phosphorylation with some agents,100 whereas fialuridine is associated with damage to mitochondrial DNA.101 341
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Figure 24-16. Steatosis associated with risperidone. In this patient, risperidone therapy was associated with significant weight gain and the development of elevated liver enzyme tests. The biopsy showed marked macrovesicular steatosis in a distribution that spared the hepatocytes adjacent to the portal areas. There was only mild spotty lobular inflammation and no fibrosis or ballooning injury that would suggest steatohepatitis. In this case, the steatosis was probably not a direct effect of the drug but was more likely to be related to the associated weight gain on therapy.
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no longer lined by endothelium. Most agents that have been associated with peliosis also cause sinusoidal dilation, either as an isolated lesion or in areas of the liver unaffected by peliosis. Oral contraceptives in particular have been associated with the peculiar pattern of zone 1 sinusoidal dilation. Fatal hepatic hemorrhage has occurred in patients with peliosis. Nodular regenerative hyperplasia (NRH) is a chronic and subtle lesion induced by some of the same agents that cause more overt forms of vascular injury. Biopsies may look almost normal on routine stains, and failure to recognize NRH may lead to unnecessary clinical workup and even splenectomy, which worsens any existing portal hypertension.108 Any “normal” appearing liver biopsy should be evaluated with trichrome and reticulin stains, particularly if the clinical team is trying to rule out cirrhosis. The reticulin stain will show the most diagnostic changes, with widened, two-cell thick liver cell plates containing large hepatocytes alternating with small, atrophic liver cells in compressed one-cell thick plates (Fig. 24-22). The trichrome stain will often show a mild to moderate degree of perisinusoidal fibrosis in the zones of compression. Sinusoidal dilation may also be present. The portal areas should also be carefully examined for evidence of portal venopathy, with slitlike or obliterated portal veins. NRH has been associated with chronic therapy with immunosuppressive agents such as azathioprine (renal transplantation),109,110 thioguanine, and mercaptopurine (Crohn disease).111 Megadoses of vitamin A have been associated with noncirrhotic portal hypertension characterized by sinusoidal fibrosis and the accumulation of lipid-laden stellate cells.112,113
Vascular Injury Patterns
Pigments and Other Cytoplasmic Changes
A variety of vascular injury patterns have been associated with drug and toxic injury (see Table 24-7). They are interrelated in that drugs that cause one type of vascular injury are often associated with others. The main types of injury include veno-occlusive disease/sinusoidal obstruction syndrome (VOD/SOS), hepatic vein thrombosis (or BuddChiari syndrome), peliosis hepatis, sinusoidal dilation, and nodular regenerative hyperplasia (see Table 24-8). Two of these patterns, VOD/ SOS and hepatic vein thrombosis, may cause hepatic necrosis secondary to hypoxic injury from venous outflow obstruction. In VOD/SOS, there is obliteration of the small hepatic veins and obstruction of the sinusoids by cell debris.102 The sinusoidal injury is difficult to recognize on routine histologic sections, but the secondary changes of hemorrhage and hepatocellular necrosis should cause the observer to look closely at the veins. The veins will be narrowed by loose connective tissue and a Masson trichrome stain can be helpful in showing the normal vein wall as a thin blue rim around the reddish-blue connective tissue plug (Figs. 24-20 and 24-21). In hepatic vein thrombosis, the larger veins are occluded by thrombi. Because a large-caliber vein may not be sampled in a percutaneous needle biopsy, the biopsy may only show the secondary changes of marked congestion, central hemorrhage, and necrosis. Chemotherapeutic agents have been associated with both hepatic vein thrombosis and VOD/SOS, whereas oral contraceptives have been associated with hepatic vein thrombosis. Pyrrolizidine alkaloids, which are still found in a number of herbal and medicinal teas, were one of the first substances to be associated with VOD/SOS following an outbreak of this disease in Jamaica in the 1950s.103 Although in the context of chemotherapy and bone marrow preparative regimens, VOD/SOS often has an acute presentation, and chronic low doses of environmental toxins such as the pyrrolizidine alkaloids can lead to a chronic injury with fibrotic obliteration of the terminal veins.104 Over time, this can lead to a pattern of fibrosis similar to cardiac sclerosis. Both oral contraceptive steroids and anabolic steroids have been associated with peliosis hepatis and sinusoidal dilation.105–107 In peliosis, the sinusoids are transformed into cystlike spaces that are
Drugs may be associated with a number of cytoplasmic changes and pigment accumulation of varying clinical significance. Barbiturates and some other drugs have been associated with a ground-glass cell type of change due to a diffuse hypertrophy of the smooth endoplasmic reticulum.114,115 This may represent an induced adaptive change in the hepatocytes but may be alarming because patients can have hepatomegaly and elevated levels of gamma glutamyltransferase. It can be easily differentiated from the ground-glass cell change of hepatitis B by specific immunoperoxidase staining for surface antigen. Diffuse hepatic glycogenosis, or glycogenotic hepatopathy, is a cytoplasmic change in which the hepatocytes are swollen and pale but not vacuolated as in steatosis. There is usually little or no inflammation (Fig. 24-23). Glycogenosis can be associated with markedly elevated transaminase levels and hepatomegaly, which can trigger biopsy. It has been associated with short courses of high-dose corticosteroids116 and has also been recently reported in patients with type 1 diabetes.117 Both the diabetic and steroid associations suggest that dysregulated glycogen metabolism may be the cause of the change. Ground-glass inclusion bodies that react positively with periodic acid–Schiff (PAS) reagent after diastase digestion have been reported after cyanamide therapy. The inclusions are eosinophilic and have a narrow halo. On ultrastructural examination, the inclusions appear to be a conglomeration of glycogen, secondary lysosomes, lipid vesicles, and degenerating organelles.118 The lesion has been reported in association with cirrhosis, although it is not clear that the cirrhosis is not due to underlying alcoholic liver disease. Finally, there is a type of hepatocellular inclusion that is intensely PAS-positive but diastase-sensitive that has been associated with polypharmacotherapy and/or disordered glucose metabolism.119 A number of pigments have been associated with drug- and toxininduced liver injury in addition to bilirubin (discussed above) and iron. Lipofuscin may be increased after long-term therapy with chlorpromazine and other anticonvulsants, phenacetin, and Cascara sagrada.63,120 Increased cell death in drug injury reactions results in the accumulation of pigment in Kupffer cells, which can be highlighted with PAS staining.
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Figure 24-17. Amiodarone toxicity. Amiodarone is associated with two distinct presentations of hepatotoxicity. The better known to pathologists is the chronic injury pattern that can mimic steatohepatitis and result in cirrhosis. Amiodarone is also associated with a fulminant acute hepatitis that may develop following high dose intravenous administration. (A) This case shows cirrhosis with small regenerative nodules and mild inflammation, mainly confined to the fibrotic bands. There is very little steatosis visible and thus resembles many other cases of end-stage liver disease from more common etiologies. (B) Focally there is ballooning injury of hepatocytes similar to that seen in alcoholic or nonalcoholic steatohepatitis. Mallory bodies are present in the adjacent cells but are difficult to identify because they blend in with the granular eosinophilic cytoplasm. (C) Ubiquitin staining demonstrates numerous Mallory bodies, present in both ballooned and nonballooned hepatocytes (antiubiquitin). (D) In a separate case of amiodarone toxicity, there is microvesicular steatosis associated with Mallory body formation and prominent perisinusoidal fibrosis.
Black, granular pigments have been reported in the liver following the use of gold compounds121,122 or after abuse of laxatives containing mercurous chloride.123 Intravenous drug abuse may lead to the accumulation of black titanium pigment.124 Polyvinylpyrrolidone may accumulate in hepatic macrophages as a granular basophilic pigment.125 It stains positively with Congo red (negative birefringence), Sirius red, and Lugol iodine solution. The most notorious drug-associated pigment is thorium dioxide, which is better known by its trade name of Thorotrast. Thorotrast was used as an x-ray contrast medium from the 1930s into the 1950s. It appears as a gray-golden, partly refractile, coarsely granular pigment in Kupffer cells and sometimes free in the extracellular matrix.126 The radioactive alpha particles emitted by Thorotrast have caused hepatocellular neoplasms of all types (Fig. 24-24).
Neoplasms A few agents have been associated with neoplasia, both benign and malignant neoplasms (see Table 24-8). With the exception of Thorotrast, which leaves evidence of its existence, there is nothing about these
eoplasms to suggest a drug or toxic origin. Thus, drug-associated n neoplasia is mainly an epidemiologic issue rather than a histopathologic one. Anabolic and contraceptive steroids have been associated with nearly the full range of neoplasms, from hepatic adenomas to hepato cellular carcinoma, cholangiocarcinoma, and angiosarcoma.127–130 There is no convincing association between contraceptive steroids and the development of focal nodular hyperplasia.131 Occupational exposure to vinyl chloride has been implicated as a cause of angiosarcoma132,133 as well as other lesions of endothelial injury such as peliosis hepatis, sinusoidal dilation, and portal fibrosis with portal hypertension.104
Grading and Staging With the exception of methotrexate, there are no specific grading and staging systems in use for drug-induced liver injury. For methotrexate, the method of Roenigk and associates134 has been in use for several decades and is still used as part of the decision to continue methotrexate therapy. The use of liver biopsy in managing methotrexate therapy 343
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B Figure 24-19. Microvesicular steatosis due to fialuridine toxicity. Microvesicular steatosis is a rare but often devastating form of liver toxicity. It is often associated with mitochondrial toxicity that may be present in other organs as well. Lactic acidosis results from a switch to anaerobic metabolism and may be fatal. Fialuridine causes mitochondrial injury by inhibition of mitochondrial DNA polymerase and by incorporation into the DNA polymer. (A) The hepatocytes are swollen and pale due to the accumulation of lipid. Only mild lobular inflammation and only rare apoptotic hepatocytes are seen. (B) The hepatocytes have a foamy appearance at high magnification. The nucleus is not displaced by the microvesicles. Despite the viable appearance of the hepatocytes, the cells are metabolically crippled, leading to fulminant hepatic failure.
C Figure 24-18. Steatosis and fibrosis related to methotrexate therapy. Chronic methotrexate therapy for collagen-vascular diseases has been associated with the development of steatosis and progressive fibrosis. Portal inflammation with interface hepatitis may also be present. The risk of fibrotic progression varies with dosage, schedule, and total dose. Patients with psoriasis may be at greater risk, but there is definitely increased risk in patients who are both obese and diabetic as well as in those with chronic alcohol consumption. Biopsies are still performed to assess progression of liver disease. (A) This surveillance biopsy shows moderate macrovesicular steatosis and little inflammation. (B) Trichrome staining reveals mild sinusoidal fibrosis. Mallory bodies and ballooning hepatocellular injury are not seen. (Masson trichrome.) (C) Staining for smooth muscle actin demonstrates positive staining consistent with stellate cell activation in the area of fibrosis. (Anti–smooth muscle actin.) 344
is an issue that is debated in the literature.135 The staging scheme is shown in Table 24-9. Although no general scheme for grading and staging drug-induced liver disease exists, it seems reasonable to adopt other existing liver disease staging systems to help describe the disease severity. Histologic features that deserve descriptive quantitation include the degrees of fibrosis, ductal paucity, hepatocellular necrosis, and inflammation (including the presence or absence of bridging necrosis).
Differential Diagnosis Drug-induced liver injury is a diagnosis of exclusion. To make the diagnosis, one must first consider the possibility. If drugs and herbal agents do not ever enter a differential diagnosis, then they can never be identified as the cause of the injury. Once considered, there are a number of other factors to consider in the evaluation of any particular injury. No pathology report should ever read merely “consistent with drug injury”
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Figure 24-20. VOD/SOS due to melphalan. Local-regional therapies for cancer offer the possibility of increasing the chemotherapeutic dose delivered to the tumor while sparing the rest of the body from side effects. In this case, VOD/SOS developed within weeks after an isolated intrahepatic perfusion with melphalan for metastatic colon cancer. (A) The central vein is narrowed, with only a small slitlike lumen remaining. A few extravasated red cells are seen around the edges of the vein, but there is no necrosis. Intrahepatic cholestasis is also present. (B) The trichrome stain clearly shows that the vein lumen is filled with a pale-blue staining loose connective tissue. The original vein wall collagen stains a darker blue. (Masson trichrome.)
because all injuries are potentially drug-related. The report should identify the pattern(s) of injury that may be present and should include some estimate of the severity of the injury. Patterns can then directly lead to pathologic differential diagnosis as outlined in Table 24-7. This process should be done as objectively as possible to avoid being swayed by available clinical information. With the pathologic differential diagnostic possibilities determined, the pathologist and the clinician should work together to establish whether drugs or herbal agents are involved in the injury and what the likelihood of drug etiology is.
Determining Causality As noted in the introductory section, the establishment of a causal relationship between a particular agent and hepatic injury is a serious matter. Furthermore, it can be difficult to decide between various competing clinical factors. In response to this, hepatologists and other experts in drug-related injuries have devised a number of clinical point scales to help establish the degree of causality. The scales in common
C Figure 24-21. VOD/SOS after bone marrow transplant. VOD and SOS are serious complications of cytoreductive therapies used to prepare patients for bone marrow transplantation usually developing within the first 30 days after transplant. This patient developed VOD/SOS 1 month after bone marrow transplant for acute myelocytic leukemia. (A) There is coagulative necrosis of hepatocytes in zone 3 associated with hemorrhage. Sinusoidal dilation and congestion are seen outside the zone of necrosis. (B) Higher magnification of the same field shows occlusion of the central vein and surrounding sinusoids with fibrin and red cells. (C) By showing the collagen of the vein wall, the trichrome stain helps to identify the occluded veins within areas of necrosis, allowing the correct diagnosis of VOD/SOS. (Masson trichrome.) Both this patient and the patient with the intrahepatic perfusion (Fig. 24-20) died within a few weeks from complications of hepatic failure. 345
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Figure 24-22. NRH due to chemotherapy. Chemotherapeutic agents are associated with a variety of lesions, including VOD/SOS, peliosis hepatis, sinusoidal dilation, and NRH. In this patient with colon cancer, the only risk factor for NRH was systemic chemotherapy. The liver was diffusely nodular on gross examination. (A) At low power, the hepatic parenchyma has a vague nodular appearance, accentuated by staining variation and sinusoidal congestion. The smaller, atrophic hepatocytes are more deeply eosinophilic than the larger hepatocytes in the regenerative areas. (B) The key to the diagnosis is the observation of alternately expanded and compressed liver cell plates on a reticulin stain. As with the routine stain, there is subtle staining variation at low magnification, with darker staining in areas where the cords are narrowed. (C) At high magnification, the nodularity is clear on the reticulin stain, with alternating zones of liver plate expansion and compression. (D) The trichrome stain frequently shows some degree of sinusoidal fibrosis in the atrophic zones, but significant fibrosis suggestive of cirrhosis is not present. (Masson trichrome.)
use are outlined in Table 24-10. Two are liver specific, the RUCAM7 and the Clinical Diagnostic Scale, or CDS.136 The Naranjo scale is not specific to the liver but is meant to be used in the evaluation of any drugrelated injury.137 All of these scales consider a similar set of factors: the timing of drug use with respect to the injury, exclusion of other potential reasons for the injury, the resolution (or lack thereof) with removal of the agent, result on rechallenge (if done), and what has been reported in the literature concerning toxicity of the agent. The Naranjo scale also considers “objective evidence” of injury, such as a biopsy, but the two liver-specific scales do not include any factors for pathology data. The scales are also not very drug specific, although they do take into consideration whether the drug has been previously reported to cause injury and if there have been multiple reports of injury. The RUCAM does treat the different biochemical injury types somewhat differently in terms of the time to the onset of injury and the clinical course. Because these scales are clinical in their orientation and do not take into consideration the pathologic pattern of injury, they are not very satisfying to the pathologist. It is still important to have a systematic 346
approach to evaluating the pathologic and clinical features of any particular case so that one can arrive at an appropriate conclusion. Dr. Irey, who was chair of the Department of Environmental Pathology at the Armed Forces Institute of Pathology, devised such a method years before the clinical scales described previously were published.138 His method is outlined in Box 24-3. Temporal Eligibility This is the first consideration. One needs to gather information about all of the potential agents, drugs and herbal, that might account for the injury. It is important to know when the agent was started, when it was stopped, and when the injury was first noted. The date of onset may precede the date the patient was admitted to the hospital or when the first laboratory studies were drawn. Agents begun after the onset of injury may be excluded from consideration. Although this may seem an obvious point, there is usually some confusion about exactly when drugs were started as well as some difficulty pinpointing the date of onset. With some rare exceptions, drugs that have been taken for
Liver Injury Due to Drugs and Herbal Agents
24
A
B
C
D
Figure 24-23. Steroid-induced glycogenosis. Corticosteroids are most commonly associated with development of steatosis in the liver. One of the rarer and potentially more significant injury patterns is hepatocellular glycogenosis, or glycogenic hepatopathy, which can develop after a short course of high-dose steroids. In this case, high-dose steroids were used to treat presumed hepatic graft-versus-host disease. The transaminases initially fell but rose abruptly after several days of therapy, prompting a liver biopsy. (A) The hepatocytes show cytoplasmic clearing, with only rare steatotic vacuoles. The change involves the entire lobule in this case. There is very little inflammation and no duct injury to suggest graft-versushost disease. (B) At higher magnification, one does not see the microvacuolation of microvesicular steatosis and the cytoplasm is not quite optically clear. Instead the “clear” spaces contain a very pale blue-gray material. (C) The cytoplasm stains intensely with periodic acid–Schiff, and this staining disappears completely after diastase digestion. (D) A second liver biopsy done 7 weeks later showed graft-versus-host disease but no evidence of glycogenosis.
many years without evidence of toxicity may be excluded as well. Some drugs, such as methotrexate, may cause a subclinical injury that does not present symptomatically until the patient has developed cirrhosis. Nitrofurantoin is another agent that may be taken for many months prior to the apparent onset of injury. Most drugs that cause injury will have been started within the past 3 months preceding the onset of injury, with some differences between the hypersensitivity and metabolic idiosyncratic agents as noted earlier. The patient may have stopped taking the medication up to a month prior to the onset of injury, and this gap does not necessarily exclude the drug from consideration. Exclusion of Competing Causes The second consideration is exclusion of competing causes. This requires a thorough clinical evaluation, including an extensive history, physical examination, and appropriate laboratory and imaging tests. The pathologic pattern of injury may help define what other diseases should be considered and excluded. The pathologic pattern may also exclude preexisting diseases or other nondrug etiologies from consideration.
For example, zone 3 confluent necrosis and canalicular cholestasis would not be compatible with chronic hepatitis C, and at the very least, they suggest that some other process is occurring. Known Potential for Injury and Precedent for Pathologic Injury Pattern The known potential for injury is an important piece of information to have, and it is a prelude to the next factor—the precedent for the pathologic injury pattern. The known potential injury relates to the incidence of injury, which is a difficult number to know with any precision. Nevertheless, reference to Table 24-8 or to any of the standard texts of drug-induced liver injury cited in the historical overview can be a good start. Beyond that, it has become a relatively simple matter to perform electronic searches of the literature. Combining the generic name of the drug with another search term such as hepatitis, hepatotoxicity, cholestasis, jaundice, or hepatic failure is usually a good way to start. Using a web-based search engine also gives the searcher access to FDA reports, books that are electronically searchable through access 347
Practical Hepatic Pathology Table 24-10. Causality Scoring Methods Author
Comments
Naranjo et al137 Not liver specific
A
Factors Considered in Method Prior reports of toxicity, timing, dechallenge, rechallenge, alternative explanations, toxicology, drug cross-reactivity, objective evidence
Danan and Benichou7
RUCAM—liver Biochemical injury type, timing of drug intake specific prior to onset and time to biochemical resolution, risk factors, age, other drugs, exclusion of other liver diseases, prior reports of toxicity, rechallenge
Maria and Victorino136
CDS—liver specific
Timing of drug intake prior to onset and time to biochemical resolution, exclusion of other liver disease, extrahepatic signs, rechallenge, prior reports of toxicity
CDS, clinical diagnostic scale; RUCAM, Roussel Uclaf Causality Assessment Method.
agreements, and other publicly available information. Drugs that are commonly used and have been on the market for many years with only rare reports of toxicity should not be considered equally with drugs that are more frequent causes of hepatitis injury. The same sources can provide information on the characteristic pathology. Most drugs have a relatively restricted spectrum of injury. Even when a particular agent has more than one pattern, usually there are some kinds of injury that are more common than others. For example, zonal necrosis is a much more common pattern of acetaminophen injury than the other injuries noted in the literature.
B Figure 24-24. Hepatic angiosarcoma due to Thorotrast. Thorotrast is a contrast agent that became notorious for its association with a variety of hepatic malignancies. This patient developed and later died from a hepatic angiosarcoma. (A) The sinusoids of the liver are infiltrated by a poorly differentiated spindle cell malignancy. Within the portal area and some of the nearby sinuses are cells that contain a pale golden refractile pigment. (B) The pigment accumulates in Kupffer cells of the liver, irradiating the nearby cells with alpha particles from the radioactive decay of the thorium. Its distinctive color and lack of staining for iron makes this pigment easy to identify as Thorotrast on routine sections.
Dechallenge/Rechallenge The factor of dechallenge refers to the idea that if a drug is causing an injury and the patient stops taking the drug, then the injury should subside. When this happens, it is circumstantial evidence of a causal relationship. However, there are many circumstances when the injury continues to the point of liver failure or, in the case of drug-related cirrhosis, may not be particularly reversible. Thus, persistence or worsening of the injury after cessation of the drug does not provide evidence for or against the drug. Rechallenge occurs rarely but is sometimes necessary when the drug is critical or not easily replaced by another agent. In the case of herbal medications, patients sometimes rechallenge
Box 24-3. Practical Considerations in Determining Causality (after Irey) Table 24-9. Staging of Methotrexate-Related Injury Stage
Description
I
Normal to mild nonspecific changes of steatosis, anisonucleosis, and portal inflammation
II
Moderate to severe steatosis, anisonucleosis, and inflammation with fibrosis up to portal fibrotic expansion
IIIA
Formation of fibrous septa
IIIB
Moderate to severe fibrosis (bridging)
IV
Cirrhosis
Adapted from Roenigk HH Jr, Auerbach R, Maibach HI, et al: Methotrexate in psoriasis: Revised guidelines. J Am Acad Dermatol. 1988;19:145–156.
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Factors to consider • Temporal eligibility • Exclusion of competing causes • Known potential for injury • Precedent for pathologic injury pattern • Dechallenge/rechallenge • Toxicologic analysis Classification by degree of certainty • Definite—Classic presentation by known toxin, no competing causes • Very likely—Nearly classic presentation, no competing causes • Probable—Classic/near-classic presentation, not all competing causes can be absolutely excluded or toxin without precedent but for which there are no competing causes • Possible—Atypical presentation or competing causes, but some features in favor of toxicity • Excluded—Agent can be reasonably excluded from consideration From Irey NS: Teaching monograph. Tissue reactions to drugs. Am J Pathol. 1976;82:613–647.
Liver Injury Due to Drugs and Herbal Agents t hemselves out of ignorance. In any case, if rechallenge causes the injury to recur, then that is excellent evidence in favor of causation. Toxicologic analysis, the last item in Irey’s method, may be useful in certain limited circumstances, but generally only if the drug is an intrinsic hepatotoxin, such as acetaminophen. For idiosyncratic toxicity, toxicology is of little value. Degree of Certainty Once these factors have been taken into consideration, one should try to assign a level of certainty to the diagnosis (see Box 24-3). Although this may not be a formal part of the diagnostic line, some part of the case discussion should focus on how likely the drug is to have caused the injury based on pattern and presentation. Drugs with No Record One final comment concerns agents that have no record of injury. This is particularly true of drugs recently added to the pharmacopeia or that are experimental agents in clinical trial situations. Herbal formulations may fall into this category as well. In these situations, most of the arguments based on pattern and precedent are difficult if not impossible to apply. One must therefore depend on careful exclusion of competing causes and examination of the pathologic changes for features that might be more suggestive of drug or toxic injury. Evaluation of injuries caused by agents of the same class is sometimes helpful. In the case of experimental agents, determination of causality is critical. It is just as important to correctly identify another etiology and exonerate the experimental agent as it is to incriminate it and cause it to be removed from clinical use.
Ancillary Diagnostic Studies Patients under evaluation for drug-induced liver injury should have a clinical evaluation that is sufficient to exclude other causes of liver disease as discussed previously. This could include serologic testing for viruses and autoantibodies as well as ceruloplasmin and alpha-1 antitrypsin levels. Molecular testing for viruses may be needed in cases of acute hepatitis to fully exclude a viral infection. The testing may have to be performed during the follow-up period, as in the case of hepatitis C virus; molecular and serologic tests may be negative during the acute phase of the illness. Imaging studies should be done as appropriate to exclude biliary obstruction and to evaluate the biliary tree for evidence of sclerosing cholangitis. The pathologist’s evaluation should be just as thorough in order to characterize the injury completely. If a patient goes for liver transplant or dies and an autopsy is performed, a small piece of liver can be frozen and set aside for biochemical or molecular studies. With a biopsy, the options for use of the tissue are more limited, but one should consider trimming a small piece for ultrastructural evaluation and/or fat stains. Fat stains may be performed on the formalin-fixed biopsy by cutting sections from the fixed tissue on a cryostat prior to processing. Depending on laboratory practice, it would be prudent to cut additional unstained sections from the biopsy at the time of first cutting in order to conserve tissue. One should have a low threshold for using special stains to evaluate drug-induced liver injury. Trichrome stains or similar collagen stains should be done almost as routinely as hematoxylin and eosin to evaluate the degree of fibrosis and discriminate between established scarring and areas of necrotic collapse. They are also useful for evaluating the veins in occlusive diseases. Reticulin stains should be done to establish the diagnosis of NRH. Iron and copper stains are not only useful for evaluating for those metals but also useful to show bile accumulation in hepatocytes and canaliculi. PAS stains can be used to characterize cytoplasmic inclusions. Acid-fast, methenamine silver, and Warthin-Starry stains should be done to help exclude unusual
infections when granulomas are present. Among the immunostains, cytokeratins 7 and 19 are useful for highlighting biliary epithelium and may help identify duct remnants obscured by inflammation or that are so damaged that they are difficult to recognize. Ubiquitin staining highlights Mallory bodies. Stains for hepatitis B will probably be useful only if the patient is known to have hepatitis B or if ground-glass cell change is focal. In situ hybridization for Epstein-Barr virus may be needed if the mononucleosis pattern is seen. Immunohistochemical phenotyping of the lymphocytes or molecular studies may be necessary to exclude lymphoma. As always, careful forethought about which stains to perform as well as conservative use of the tissue is important in the pathologic evaluation of possible drug injury.
24
Genetics There are a number of recognized genetic factors associated with susceptibility to increased injury from drugs. Genetic differences between individuals provide one of the mechanistic explanations of idiosyncratic hepatotoxicity. Halothane was one drug in which early evidence suggested a genetic component both in humans and in animal models. Otsuka and coworkers identified human leukocyte antigen (HLA) associations in Japanese patients who developed halothane hepatitis.139 In that population, the DR2 locus was more common and the Bw44 locus was less common in patients with jaundice. HLA associations have been reported in amoxicillin-clavulanate injuries from patients in Belgium140 and Scotland.141 These groups independently identified the DRB1*1501 locus as associated with injury from this antibiotic. Other drugs with injuries associated with HLA antigens include nitrofurantoin,142 clometacin,143 chlorpromazine, diclofenac, and the tricyclic antidepressants.144 Defects in drug-metabolizing enzymes have also been associated with a predisposition to hepatotoxicity with certain drugs. These include defects in the cytochrome P450 family of enzymes and in other processing enzymes that are responsible for detoxification of drugs. Deficiency of CYP2D6 has been associated with toxicity from perhexiline.145 Enhanced activity of this enzyme has been correlated with chlorpromazine injury in conjunction with defects in sulfoxidation.146 Deficiency of the N-acetyltransferase-2 (NAT2) enzyme lies at the root of the slow acetylation phenotype. Individuals who are NAT2-deficient have increased susceptibility to injury from the sulfonamides147,148 and dihydralazine.59 The recent sequencing of the human genome and the completion of the National Human Genome Research Institute’s HapMap project have sparked interest in using large-scale single nucleotide polymorphism analysis to identify people who might be susceptible to drug injury of all types. This approach would complement the targeted gene methods used in the studies described earlier. At this point, the major barrier to whole genome screening lies in accrual of sufficient numbers of validated cases and controls so that the genomic analysis is meaningful.149
Treatment and Prognosis The first treatment for drug-induced liver injury is to stop the administration of the suspect agent. This usually occurs as soon as there is a suspicion that a drug may be involved and therefore is usually done before a biopsy is performed. Sometimes a drug is continued until a biopsy is performed and the degree of injury can be assessed, as in the case of methotrexate. More rarely, the biopsy suggests a diagnosis of drug injury that had not previously been considered, and so the drug is stopped only after the biopsy has been performed. Many injuries will resolve once the drug has been stopped, and the speed of recovery depends on the type of injury and the overall severity. General supportive therapy for liver injury is used on a case-by-case basis. Not all drug injuries have the same prognosis. The late Dr. Hyman 349
Practical Hepatic Pathology Zimmerman propounded a rule of thumb based on his clinical experience that jaundice in the presence of a hepatocellular injury (elevated transaminases) was the most serious injury and resulted in approximately 10% mortality.5 This rule, known as “Hy’s law,” has recently been tested and shown to be essentially correct. Two large-scale studies, one in Spain9 and one in Sweden,150 evaluated mortality as a function of biochemical presentation. In the Spanish study, 11.7% of patients with hepatocellular jaundice progressed to liver transplantation or death, whereas in nonjaundiced patients with hepatocellular injury the figure was only 3.8%. In the Swedish study, 12.7% of patients with hepatocellular injury were either transplanted or died, compared with 7.8% of patients with cholestatic injury. Of the patients with hepatocellular injury, those that died or received transplants were older and had higher bilirubin levels, higher AST and ALT, and a higher ratio of AST to ALT. Transplantation has been used since its inception for acute liver failure due to drugs and toxins. Using the UNOS registry data, it was estimated that about 15% of transplants for acute liver failure between 1990 and 2002 had drug injury as a cause. Nearly 50% of those cases were due to liver failure from a single drug, acetaminophen.36 There are few specific interventions that are used in drug-induced liver injury. N-Acetylcysteine has been used for 40 years to counter acetaminophen toxicity by replenishing depleted stores of glutathoine.151,152 The efficacy of this agent in acute liver failure from other causes is being investigated at this time by the Acute Liver Failure Study Group.153,154 Corticosteroids are sometimes used to treat drug-induced liver injury, particularly hypersensitivity types of idiosyncratic injury, but there are no controlled clinical trials that have confirmed the efficacy of steroid therapy in this situation. The prognostic significance of the histologic findings on biopsy has not been broadly examined in drug-induced liver injury and most would apply what is known about liver disease in nondrug injury etiologies to the drug injury situation. Cirrhosis and massive hepatocellular necrosis portend a poor outcome no matter what etiology is responsible. One interesting study surveyed the opinions of 29 expert hepatologists concerning 39 clinical, biochemical, and pathologic disease features that were indications of severe drug-induced liver disease.155 Participants were asked rank features by severity. Of the top 10 features, 6 were pathologic findings: hepatocellular carcinoma, veno-occlusive disease, cirrhosis, sclerosing cholangitis, ductopenia, and bridging fibrosis. With respect to particular histologic features, Bjornsson and colleagues reviewed 570 case reports of drug-induced liver injury that had made note of eosinophilia (both peripheral and in biopsies) and hepatocellular necrosis on biopsy.156 Patients who survived were more likely to have eosinophils (in either site) and less likely to have hepatocellular necrosis. Katoonizadeh and associates looked at biopsies from patients in acute and subacute liver failure and found an association between poor outcome (death/transplantation) and the degree of hepatocellular necrosis, increased numbers of hepatocyte progenitor cells, and reduced numbers of proliferating hepatocytes.157 These findings are encouraging; other tissue-based prognostic factors may yet be discovered for drug- and herbal-induced liver injury.
Acknowledgments The photomicrographs in Figures 24-1 to 24-7, 24-9, 24-11 to 24-15, and 24-17 were obtained from cases referred to and confirmed by the Drug-Induced Liver Injury Network (https://dilin.dcri.duke.edu/). Suggested Readings oodman ZD. Drug hepatotoxicity. Clin Liver Dis. 2002;6:381–397. G Ishak KG, Zimmerman HJ. Morphologic spectrum of drug-induced hepatic disease. Gastroenterol Clin North Am. 1995;24:759–786.
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Kaplowitz N. Idiosyncratic drug hepatotoxicity. Nat Rev Drug Discov. 2005;4:489–499. Lee WM. Drug-induced hepatotoxicity. N Engl J Med. 2003;349:474–485. Wilke RA, Lin DW, Roden DM, et al. Identifying genetic risk factors for serious adverse drug reactions: Current progress and challenges. Nat Rev Drug Discov. 2007;6:904–916.
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