Acute and chronic hepatitis

Seminars in Diagnostic Pathology (2006) 23, 132-148

Acute and chronic hepatitis Arief A. Suriawinata, MD,a Swan N. Thung, MDb From the aDepartment of Pathology, Dartmouth-Hitchcock Medical Center, Lebanon, New Hampshire; and the b Department of Pathology, The Lillian-Henry M. Stratton and Hans Popper, The Mount Sinai Medical Center, New York, New York. KEYWORDS Acute hepatitis; Chronic hepatitis; Viral; Steatohepatitis; Autoimmune; Drug-induced

Most liver biopsies performed today are for grading and staging of chronic viral hepatitis and steatohepatitis; there are uncommon indications for liver biopsy in the setting of acute hepatitis. Pathologists must have a broad knowledge of many forms of acute and chronic hepatitis, as well as their variations; these include viral hepatitis, autoimmune hepatitis, drug-induced hepatitis, metabolic diseases, and reactive hepatitis secondary to systemic disease processes. In this article, the authors review the pathological features of acute and chronic hepatitis. © 2006 Elsevier Inc. All rights reserved.

Despite numerous clinical developments for the diagnoses and management of patients with liver disease, direct examination of liver tissue through liver biopsy remains an important part of management of liver diseases. The use of liver biopsy has changed over the years, from focusing largely on the diagnosis to assessing patients for therapy and monitoring patients receiving established or new treatments. Today, most liver biopsies are performed for chronic viral hepatitis and nonalcoholic steatohepatitis to assess liver damage and/or response to therapy.1 Acute hepatitis is usually not an indication for liver biopsy, but if there is doubt about the clinical diagnosis, etiology of elevation of liver enzymes, or even a mistaken working diagnosis, biopsies with acute hepatitis will be encountered by the pathologist. Liver biopsy is an invasive technique which requires a skilled operator, and all possible safeguards to minimize the risk of complications should be undertaken. The specimen may be obtained by one of several routes and methods, such as blind percutaneous or ultrasound-guided transthoracic biopsy and transjugular biopsy. Adequate size of the specimen minimizes sampling error, especially in the staging Address reprint requests and correspondence: Swan N. Thung, MD, The Mount Sinai Medical Center, Department of Pathology, Box 1194, One Gustave L. Levy Place, New York, NY 10029. E-mail address: [email protected].

0740-2570/$ -see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1053/j.semdp.2006.11.001

evaluation of chronic hepatitis and the presence of cirrhosis. Sampling from subcapsular parenchyma in chronic hepatitis may lead to overstaging, and sampling entirely from a regenerative nodule in cirrhosis may lead to understaging of the extent of fibrosis. The number of portal tracts is proportional to the total length of the specimen obtained; therefore, liver biopsy should be at least 1.5 cm in total length or otherwise another pass is recommended.2 In this review, the authors provide an overview of the pathological features of acute and chronic hepatitis, including significant differential diagnoses.

Acute hepatitis Acute hepatitis may present in various manners; it may be asymptomatic or subclinical and remain undiagnosed; it may present with influenza-like or gastrointestinal symptoms, which is the typical (classical) acute hepatitis; or, it may even present as fulminant hepatic failure. In asymptomatic patients, viral infection is only recognized in retrospect after serologic testing. Conventionally, acute hepatitis is separated from chronic hepatitis on the basis of duration, using 6 months as a cutoff; nevertheless, histological examination often is crucial in identifying the morphologic fea-

Suriawinata and Thung

Acute and Chronic Hepatitis

Figure 1 Acute hepatitis with diffuse mononuclear cell infiltrates, acidophilic bodies, ballooned hepatocytes and spotty necrosis (H&E, ⫻100).

ture of hepatitis. In contrast to patient with chronic hepatitis, the typical patient with acute hepatitis has a fairly well defined onset with anorexia, nausea, vomiting, mild pyrexia, right upper quadrant discomfort, and profound malaise. This general picture can be produced by a wide variety of infectious and injurious agents, but, in practical terms, the designation is generally employed for cases caused by hepatotropic or nonhepatotropic viruses or drug reactions. Acute viral hepatitis A and E account for the majority of cases, followed by drugs and toxins. Therefore, knowledge of the patient’s travel history, medication, immunologic status, and serologic studies are often helpful. Acute hepatitis with submassive or massive hepatic necrosis presents with signs, symptoms, and biochemical test results of acute hepatitis with jaundice, coagulopathy, and slow or rapid progression to hepatic encephalopathy and coma. As the disease progresses to hepatic failure, the initially enlarged liver may decrease in size, the markedly elevated aminotransferase activities may decline, and the prothrombin time and serum bilirubin rises.

133 thickened and occasional hepatocellular rosettes may appear. Hepatocyte nuclei often show prominent nucleoli and increased variation in size. When overt multinucleation occurs, resembling syncytial giant cell, the term giant cell hepatitis is often used; which is rarely of proven viral origin and is more characteristic of acute hepatitis in neonates. Two types of cell death can be distinguished by morphologic features, apoptosis, and ballooning degeneration, although it is likely that these are two ends of a spectrum with possible intermediate forms.3 Apoptosis involves shrinkage, nuclear disassembly, and fragmentation of the cell into discrete bodies with intact plasma membranes, which are then rapidly phagocytosed by neighboring Kupffer cells. In cytolytic necrosis, manifested histologically by ballooning degeneration, the hepatocytes become swollen, rounded, and pale staining as the result mainly from dilation of the endoplasmic reticulum. This is a consequence of loss of mitochondrial function and resultant ATP depletion, leading to loss of ion homeostasis and plasma membrane integrity.4 The cytoplasm is partially rarefied, particularly along the cellular periphery, and the cytoplasmic remnants clump around the nucleus; cell membranes are frequently indistinct. Ballooned hepatocytes undergo lytic necrosis which is not visible, but the occurrence can be inferred to small foci of stromal collapse that are accompanied by collections of lymphocytes and Kupffer cells, ie, spotty necrosis. The degree of ballooning degeneration varies across the lobule, although classically the centrilobular region is the most severely affected. In addition to hepatocyte injury and regeneration, there are varying degrees of cholestasis, Kupffer cell activation, ductular proliferation, and bile duct damage. Intracanalicular or cytoplasmic cholestasis is usually not a prominent feature of acute hepatitis, except for some cases referred to as acute cholestatic hepatitis (often are caused by drugs; see cholestatic hepatitis section) or late in the course of acute hepatitis or acute hepatitis A. The histologic findings include prominent bile plugs in bile canaliculi accompanied by cholestatic rosettes (Figure 2), and conspicuous

General histology of acute hepatitis The major histologic changes of acute hepatitis are located in the parenchyma, and are characterized by diffuse mononuclear lobular inflammation, spotty necroses, panlobular disarray, markedly increased cellularity, and pleomorphism of the hepatocytes (Figure 1). The latter is due to a combination of diffuse hepatocellular degeneration, necrosis, collapse, regeneration, and inflammation. The normal orderly arrangement of the liver cell plates is disturbed, and the hepatocytes display irregularities in their size, shape, and staining characteristics. Hepatocyte regeneration is manifested by mitoses, multinucleation, and crowding of the periportal cell plates by small, uniform, clear, or basophilic hepatocytes. Liver cell plates become irregularly

Figure 2 Cholestatic rosettes with bile plugs in dilated bile canaliculi surrounded by several hepatocytes (H&E, ⫻400).

134 ductular reaction with associated neutrophils-rich portal inflammation. Activation of sinusoidal lining cells, “the sinusoidal reaction,” particularly Kupffer cells, may be noted throughout the lobules in acute hepatitis. Activated Kupffer cells may contain phagocytosed cellular debris and lipofuscin. Endothelial cells may contain punctuate iron deposition. The portal tracts may or may not be infiltrated by lymphocytes and macrophages, with few scattered plasma cells, eosinophils, and neutrophils, but significant portal fibrosis or ductular proliferation is absent. True piecemeal necrosis and periportal fibrosis as seen in chronic hepatitis are not present. Substantial areas of parenchyma may undergo necrosis or apoptosis, referred to as confluent necrosis. Confluent necrosis may affect part, most frequently acinar zone 3, or the entire acinus. Furthermore, hepatitis may be complicated by bridging necrosis and collapse, which connects portal tracts with central hepatic venules, and is easily mistaken for fibrous septa of chronic hepatitis. Orcein stain may be utilized in this situation to distinguish the active septa of fibrosis that contain elastic fibers from the passive septa of collapse that do not. Reticulin stain may be utilized to highlight the condensation of reticulin fibers in collapse area. Trichrome stain is generally not discriminatory in this situation. In addition, although bridging necrosis can usually be accurately identified in biopsy specimens, its precise distribution may be difficult to define, particularly because the bridges may be irregularly dispersed across the liver. The band-like areas of hepatocyte loss and collapse consist of inflammatory cells, blood-filled sinusoids, and reticulin fibers, but little if any fibrous tissue and elastic fibers, as seen on reticulin, trichrome, and Victoria blue or orcein staining. With extensive lobular necrosis, ductular structures are noted, emanating from the periportal region. These have been identified in numerous studies as a part of the progenitor cell response, and are comprised of cells capable of differentiating into either hepatocytes or bile ducts.5

Acute hepatotropic viral hepatitis The classical causes of acute hepatitis are the hepatotropic viruses. Four well-known hepatotropic viruses are hepatitis A, B, C, and E; hepatitis B infection may be further complicated by coinfection or superinfection with hepatitis D. In acute hepatotropic viral hepatitis, the serum levels of transaminases are typically elevated five-fold or more. The degree of increase does not always correlate well with the extent of hepatocyte damage or the outcome of the hepatitis.6 Conjugated hyperbilirubinemia is invariably present, and the alkaline phosphatase is usually only mildly elevated. The diagnosis can be confirmed and the exact etiology established by determination of specific viral antigens and antibodies. Liver biopsy is rarely indicated for either diagnosis or prognosis.

Seminars in Diagnostic Pathology, Vol 23, No 3/4 Some affected patients may present with deep jaundice, pruritus, and elevated serum alkaline phosphatase levels; this is referred to as cholestatic hepatitis. The clinical course of this variant is typically protracted. All hepatitis viruses generally produce a similar morphologic picture characterized by diffuse hepatocyte injury and necrosis together with a predominantly mononuclear inflammatory response, predominantly T-cell lymphocytes, which reflects the role of cellular immunity in the pathogenesis of hepatitis. Hepatocellular damage and inflammation are usually most severe in acinar zone 3. Although interface hepatitis, formerly known as piecemeal necrosis, is a defining feature of chronic hepatitis, very similar periportal necrosis is found in acute hepatitis. Typical features of hepatitis A include a periportal predominance of hepatocellular injury and necrosis and a conspicuous portal and periportal inflammatory infiltrate that contains abundant plasma cell. Irregular dilation of ductules has also been described in some cases of hepatitis A.7 The general histologic appearances of acute hepatitis B infection are generally similar to those of other forms of viral hepatitis.8 However, lymphocytes and macrophages sometimes in close contact with hepatocytes (peripolesis) or invaginate within hepatocytes (emperipolesis), which may reflect the immunologic nature of the cell damage, are often seen. Hepatocytes and its nuclei show moderate pleomorphism. The presence of ground glass hepatocytes, as well as immunohistochemical reactivity for hepatitis B surface and core antigens, indicate chronic disease. Coinfection or superfinfection with hepatitis D virus enhances the severity of hepatitis B9 and are responsible for either severe acute hepatitis or exacerbation in a patient with chronic hepatitis B. Acute hepatitis C may have no distinguishing features, or there may be some distinguishing features, such as prominent infiltration of sinusoids by lymphocytes in the absence of severe liver-cell damage, so-called “beads on a string,” similar to that seen in infectious mononucleosis.10 Features that are usually seen in chronic hepatitis, notably lymphoid follicles, steatosis, and bile duct damage, may be seen as early as few weeks of onset. In parenterally acquired hepatitis B and C, birefringent spicules of talc as a result of intravenous drug abuse may be found in portal tracts.11

Acute nonhepatotropic viral hepatitis Nonhepatotropic viruses infect primarily other organs and tissues and involve the liver as part of a disseminated infection. In normal individuals, these organisms typically give rise to a mild and clinically insignificant hepatitis that is overshadowed by other manifestations; only rarely does severe or clinically evident liver disease develop. Patients with HIV, AIDS, immunosuppression, cancer, organ transplant, and neonates are prone to more serious liver involvement. Characteristic changes as discussed below may be seen in many nonhepatotropic viral infections, against the background of relatively mild nonspecific alterations.

Suriawinata and Thung

Acute and Chronic Hepatitis

Figure 3 EBV hepatitis showing infiltration of sinusoids by atypical lymphocytes in single file arrangement (H&E, ⫻200).

Diffuse hepatocellular damage is mild or absent, and hepatocytes in general appear normal. In most instances, except for Epstein Barr virus (EBV) hepatitis, “punch-out” focal necroses are prominent. Microvesicular steatosis may be seen, but cholestasis is usually absent. Sinusoidal lining cells are enlarged, and mononuclear inflammatory cells infiltrate the portal tracts and sinusoidal lumina, but are usually not in contact with hepatocytes. The specific diagnosis of the type of viral infection can usually be made by serologic tests, viral cultures, immunohistochemical staining using specific antibodies, in situ hybridization, or electron microscopy. Cytomegalovirus (CMV) hepatitis in immunocompetent patients is often part of multiorgan infectious process. Rare cases of fulminant liver failure have been described in this population.12 Neither viral inclusions nor immunohistochemically demonstrable CMV antigen are generally seen in these patients.13 In immunocompromised patients, CMV infection may be acquired through primary infection, reactivation, or superinfection by a new strain in previously seropositive patient.14 Although any organ may be involved in these patients, hepatic involvement may predominate, particularly in liver transplant patients. It is characterized by scattered cytomegalic cells with nuclear and cytoplasmic inclusions involving hepatocytes, bile duct epithelial cells, Kupffer, or endothelial cells. Sometimes, inclusions are not found and focal necrosis with clusters of neutrophils, resembling a microabscess, is seen. In neonatal/perinatal CMV infection, in addition to the findings described above, other alterations, ie, portal inflammation, marked cholestasis, giant cell transformation, focal necrosis, and prominent extramedullary hematopoiesis, may also be seen.15 In infectious mononucleosis, dense accumulation of atypical lymphocytes are found in the portal tracts and sinusoids, which may resemble leukemia or extramedullary hematopoiesis (Figure 3). Small foci of hepatocellular necrosis and increased mitoses may be seen, but diffuse hepatocellular damage that is characteristic of acute viral hep-

135 atitis is absent.16 Small noncaseating granulomas have been described in EBV and CMV infections.17 Herpes simplex virus hepatitis is usually seen in immunocompromised patients as part of disseminated infection.18 Clinically, patients may have concomitant oral or mucosal herpetic lesion with markedly elevated transaminases and hepatomegaly. Rapid progressive course with high mortality is common; therefore, liver biopsy may be invaluable for diagnosis. Herpes simplex, varicella, and varicella zoster virus infections cause punch-out necrosis or when severe, large areas of coagulative hemorrhagic necrosis, with or without intranuclear inclusions (Cowdry types A and B) in the adjacent hepatocytes. Inflammation is generally minimal. Immunohistochemistry, viral culture, and in situ hybridization help to confirm the diagnosis. Adenovirus hepatitis is usually seen in immunocompromised patients, particularly children. Concomitant pneumonia and diarrhea are indication of disseminated infection.19 Histologically, it is characterized by patchy areas of necrosis and “blueberry” basophilic intranuclear inclusions. Inflammatory infiltrate is confined to necrotic areas and consists of neutrophils. Widespread midzonal or random necrosis often mimics that of herpes infection. Immunohistochemistry, electron microscopy, and viral culture are useful diagnostic aids. Viral hemorrhagic fevers produce similar liver pathology regardless of the type of virus, ie, multiple foci of coagulative necrosis with minimal inflammation in random or midzonal distribution.20 Macrophages can be seen surrounding some of the necrotic foci. Steatosis is variable, and cholestasis is usually prominent. Multinucleated giant hepatocytes may be seen in a number of viral infections, particularly in infants. Syncytial giant cell with numerous nuclei have been associated with paramyxovirus infection.21 Rubella and reovirus infections in neonates may lead to paucity of bile ducts.22

Drug-induced acute hepatitis Most hepatic drug reactions occur in a small number of individuals, making them difficult to detect at the time of drug development and representing an important challenge for safety in drug development.23 Most drug reactions are unrelated to dose (idiosyncratic hepatotoxicity), which represent hypersensitivity reaction or genetically determined variations in drug metabolism. Acquired (gender, nutrition, pregnancy, alcohol abuse, liver and extrahepatic diseases) and genetic factors influence the individual susceptibility to drug hepatotoxicity. There are generally no specific markers or tests for the diagnosis of drug-induced liver injury. Therefore, the diagnosis relies entirely on circumstantial evidence and elimination of other obvious causes. The list of drugs that classically may cause a hepatitis-like picture is very long, and virtually any drug must be considered in the differential diagnosis. A careful history is essential and should include all drugs taken over the last several months. The latent period between drug exposure and onset of

136 symptoms may vary from several days to a few months. Exposure to hepatitis viruses should be ruled out and suspicion of drug-induced hepatitis in any patient with liver disease without obvious cause is important. Commonly used drugs, such as antimicrobials, nonsteroidal antiinflammatory drugs (NSAIDs), antihypertensives, antidiabetic agents, anticonvulsants, lipid-lowering agents, and psychotropic drugs, may potentially be hepatotoxic (Table 1). Drugs can reproduce practically the whole spectrum of liver diseases and should be considered in the differential diagnosis of any patient with hepatobiliary disease. In the absence of histological data, the preferred term is liver injury. According to the international panel, acute druginduced liver injuries can be classified in three groups using biochemical criteria based on serum alanine aminotransferase (ALT) and alkaline phosphatase (AP) and their ratio24: acute hepatocellular injury, acute cholestatic liver injury, and mixed pattern acute liver injury. This classification has the advantage of separating types of hepatitis with different courses and prognostic features. Acute hepatocellular injury is defined by ALT over two times the upper limit of normal range or ALT/AP ratio of ⱖ5. Acute cholestatic liver injury is characterized by an isolated increase of AP over two times the upper limit of normal range or by an ALT/AP ratio of ⬍2, whereas mixed pattern acute liver injury is characterized by an ALT/AP ratio between 2 and 5. Acute hepatocellular injury, the most common form of hepatic damage caused by drugs, generally conveys no specific clinical features and mimics acute viral hepatitis. Discontinuation of the treatment is usually followed by complete recovery within 1 to 3 months. Sometimes fulminant course occurs, often promoted by continuation of treatment despite the occurrence of jaundice.25 In this regard, drug-induced hepatitis is often more fulminant and fatal than acute viral hepatitis. It is associated with a 90% mortality rate unless emergency liver transplantation can be performed. In rare cases, progression of disease following drug withdrawal has been described.25 No definite histologic changes distinguish acute druginduced hepatitis from acute viral hepatitis; however, a few alterations may be helpful in the differential diagnosis, such as prominent eosinophils and granulomas, sinusoidal dilation, and fatty change. Prominent eosinophilic infiltration is seen classically in chlorpromazine-induced hepatitis.26 Granulomas in portal tracts or parenchyma may be seen either alone or in association with hepatitis. In most cases, hepatocyte necrosis is spotty, but in more severe cases, sharply demarcated perivenular or confluent necrosis and progression to multiacinar and massive hepatic necrosis can occur. The degree of canalicular or intracellular cholestasis varies but often is more severe than in acute viral hepatitis. See section below for acute cholestatic injury.

Cholestatic hepatitis The term cholestatic hepatitis is characterized by unusually severe and prolonged clinical and biochemical cholesta-

Seminars in Diagnostic Pathology, Vol 23, No 3/4 sis. Cholestatic hepatitis includes acute or unresolved viral or alcoholic hepatitis, drug-induced cholestasis or druginduced cholestatic hepatitis, and rare cases of chronic hepatitis with cholestasis. Cholestasis remains one of the most common and serious manifestations of drug-induced liver injury.24 These adverse reactions occur because the liver is the primary organ involved in uptake, metabolism, and excretion of foreign compounds (xenobiotics). The molecular basis for drug-induced cholestasis remains unclear, but current concepts regarding the function and regulation of drug and xenobiotic transport in hepatocytes and cholangiocytes provide insight into potential mechanisms for druginduced transporter dysfunction.27 Acute cholestatic liver injury is divided by two subtypes: pure (bland) cholestasis and cholestatic hepatitis.24 Pure cholestasis is characterized by pruritus and jaundice with generally normal or only slightly increased transaminases. It is often observed with a few drugs, mainly sex steroid derivatives, cytarabine, and azathioprine. Acute cholestatic hepatitis associates cholestasis with clinical features of acute hepatitis, such as pain and hepatic tenderness, and frequently mimics the features of biliary obstruction or cholangitis. Acute cholestatic hepatitis represents the second most common type of drug-induced injury and involves hundreds of agents. The prognosis of cholestatic hepatitis is generally good, although it may have a prolonged clinical course and resolve rather slowly, depending on the cause. Histologically, cholestatic hepatitis shows the characteristic changes of acute hepatitis, including panlobular disarray, increased cellularity, degenerative and regenerative changes of hepatocytes, and cholestasis. There is diffuse hepatocellular damage with eosinophilic degeneration, swelling, and focal necroses, as well as inflammatory infiltration and activation of sinusoidal lining cells throughout the lobules. In prolonged cases of cholestasis, hepatocytes form rosettes around dilated bile canaliculi. Cholestasis is less conspicuous than in large bile duct obstruction except in drug-induced cholestasis. The portal tracts are slightly expanded by inflammatory cells, predominantly lymphocytes and macrophages and scattered neutrophils. Fibrosis of portal tracts is mild. Proliferation of bile ducts and neutrophils are mild in comparison to large bile duct obstruction.

Residual hepatitis Acute hepatitis often resolves clinically in a few months, but residual changes may persist for many months.28 Sometimes, however, a liver biopsy is taken late in the course of hepatitis, for example, 4 to 6 months after the acute episode in a patient with residual liver abnormalities. In these patients, it is important to recognize the histologic changes of residual or prolonged hepatitis. At late stage of acute hepatitis, diffuse hepatocellular damage and inflammation have subsided, except for mild pleomorphism of hepatocytes, irregular cell plates, and a few foci of lobular necrosis and inflammation, primarily in centrilobular areas. Clusters of

Suriawinata and Thung Table 1

Acute and Chronic Hepatitis

137

Drug-induced injury

Drug

Pattern

Comments

Antibiotics Beta lactams

C, H, M, G

Tetracyclines Macrolides Sulfonamides Quinolones

F, HF C C, H, M, G C, H, M, G

Nitrofurantoin

C, H, M, G C H

Cholestasis may persist months/years after withdrawal. Ductopenia and vanishing bile duct syndrome may occur in prolonged cholestasis. Dose-related. Minocycline causes hypersensitivity, ie, hepatitis, eosinophilia, dermatitis. All erythromycin esters can produce cholestasis. Prominent portal eosinophilic infitrate. Co-trimoxazole causes numerous forms of liver injury. Risk increased in HIV patients. Most associated with mild cholestatic or mixed injury. Norfloxacin associated with eosinophilic necrotizing granulomatous hepatitis. All types of injury have been reported and may rarely cause chronic hepatitis with features similar to autoimmune hepatitis Rare Rare

H, G H H M

Resemble acute viral hepatitis, can be severe. Increased risk of hepatotoxicity when combined with isoniazid. Increased risk of hepatotoxicity in combination therapy. Rarely cause hepatotoxicity.

Chloramphenicol Clindamycin Antituberculosis agents Isoniazid Rifampicin Pyrazinamide Ethambutol Antifungal agents Azole Terbinafine Amphotericin B Flucytosine Antiviral agents Protease inhibitor NRTI NNRTI Antiparasitic agents Albendazole Mebendazole Thiabendazole Niclofan Pentamidine Amodiaquine NSAIDs Aspirin Diclofenac Ibuprofen Indomemethacin Sulindac Antihypertensive agents Methyldopa Beta blockers Ca channel antagonists Hydralazyne Thiazides ACE inhibitor Drugs in diabetes mellitus Glucosidase inhibitors Metformin Human insulin Sulfonylureas Thiazolidinediones Lipid lowering agents Statins Fibrates Anticonvulsants Phenytoin

H, M, C, HF Potent inhibitors of cytochrome P450 enzymes. All have been associated with hepatotoxicity. C, H Have been associated with prolonged liver injury. H Rarely associated with hepatotoxicity. H Hepatotoxicity when used in combination with other antifungals. H H, S H

Ritonavir has a higher risk of hepatotoxicity. Zidovudine and didanosine may cause fulminant hepatic failure and microvesicular steatosis. Nevirapine, efavirenz, and delavirdine have been associated with hepatotoxicity.

H, M H, M M C H H, HF

Mild hepatotoxicity Mild hepatotoxicity Prolonged cholestatic hepatitis, vanishing bile duct syndrome. One case report. High incidence of mild to moderate liver enzyme elevation. Rare

H, HF H H H, C C, H

Dose-dependent, Reye’s syndrome. Women, persons with osteoarthritis may be susceptible. Rarely cause vanishing bile duct syndrome. Rare massive hepatic necrosis. Hypersensitivity features common, rash, nephrotoxicity, shock syndrome.

H, C, S, G

Methyldopa-related liver injury is best characterized. Low hepatotoxic potential except labetolol, which can cause severe acute hepatitis. Diltiazem also associated with cholestasis and granulomatous hepatitis.

H H, C, G C C

Rare Rare. Losartan may be used in treating portal hypertension.

H,C C M C, H, G H, HF

Acarbose have been associated with dose-related hepatotoxicity. Rare Rare Predominantly cholestasis. Troglitazone causes fulminant hepatic failure, rosiglitazone and pioglitazone cause hepatocellular injury.

H, M

Elevation of liver enzymes seen in approx. 3% of recipients, dose dependent, within 3 months of therapy. Serious injury is rare. Fenofibrate is associated with rare cases of autoimmune hepatitis, fibrosis, and ductopenia.

H, C, HF

H

Focal necrosis with sinusoidal lymphocytosis.

138 Table 1

Seminars in Diagnostic Pathology, Vol 23, No 3/4 (continued)

Drug

Pattern

Comments

Carbamazepine Vaproic acid Felbamate Topiramate Psychotropic drugs Chlorpromazine Haloperidol Clozapine Benzodiazepine MAO inhibitors Tricyclic antidepressants SSRIs

G, C H, S HF H

Granulomatous hepatitis, cholestasis, rarely vanishing bile duct syndrome. Rarely acute liver failure with microvesicular steatosis. Acute liver failure in more than 30 reported cases. Rare acute liver failure.

C C H, C H H

Vanishing bile duct syndrome. Vanishing bile duct syndrome. Rare. May be associated with hepatic failure. May also cause chronic hepatitis. Rare except with iproniazid.

H, C H

Amitriptyline, imipramine may cause vanishing bile duct syndrome. Rare, may also cause chronic hepatitis.

H, hepatocellular; C, cholestatic; M, mixed; G, granulomatous; F, fatty liver; HF, hepatic failure; S, steatosis; NRTI, nucleoside reverse transcriptase inhibitor; NNRTI, non-nucleoside reverse transcriptase inhibitor.

PAS-stained, diastase-resistant macrophages are observed in parenchyma (Figure 4). Residual or prolonged hepatitis may be difficult to differentiate from nonspecific reactive hepatitis. Localized collapse, scarring, and regeneration following severe hepatitis with bridging or panacinar necrosis sometimes produce a histological picture reminiscent of cirrhosis. Localized collapse and scarring with immature collagen deposition can be seen in trichrome stain as paler blue staining area if compared with mature collagen fibers in portal tracts. In addition, condensation of reticulin fibers is seen in collapsed areas, without true deposition of reticulin fibers usually seen in cirrhosis.

Nonspecific reactive hepatitis Nonspecific reactive hepatitis is defined as mesenchymal tissue reaction in the liver in response to extrahepatic ab-

normalities or unknown causes. There is no primary parenchymal liver damage, but nonspecific reactive hepatitis accompanies extrahepatic biliary disorders, gastrointestinal diseases, malignancies, and infectious diseases.28 The alterations consist of activation of sinusoidal lining cells with prominent Kupffer cells, small foci of necrosis of isolated hepatocytes with accumulation of macrophages and other inflammatory cells, and infiltration of portal tracts by scattered mononuclear cells. The inflammatory infiltrates in only slightly enlarged portal tracts are not as dense as in chronic hepatitis, usually do not involve all portal tracts, and are not accompanied by interface hepatitis or fibrosis. Scattered hepatocytes also may contain microvesicular or macrovesicular fat globules. Nonspecific reactive hepatitis with steatosis, increased variation in size, and staining quality of hepatocyte nuclei, sinusoidal dilation, and poorly developed granulomas are often seen in the liver of patients with acquired immunodeficiency syndrome (AIDS).29 The granulomas may be difficult to recognize, but special stains frequently show large numbers of microorganisms such as M. avium-intracellulare.

Differential diagnosis and conditions mimicking acute hepatitis

Figure 4 Clusters of macrophages containing D-PAS reactive material in resolving acute hepatitis (D-PAS reaction, ⫻200).

The advancement of imaging has reduced the need for liver biopsy in acutely jaundiced patients. Biopsy is often still performed when the cause of a presumed intrahepatic jaundice is in doubt and the need to distinguish acute and chronic hepatitis exists. The differential diagnoses of acutely jaundiced patient include acute viral and drug-induced hepatitis, chronic liver disease with acute exacerbation, bile duct obstruction, sepsis, and various other forms of intrahepatic cholestasis (Table 2). In addition, there are liver diseases that are unique in pregnancy: intrahepatic cholestasis of pregnancy, acute fatty liver of pregnancy, and toxemia

Suriawinata and Thung Table 2

Acute and Chronic Hepatitis

139

Differential diagnoses and conditions mimicking acute hepatitis

Diagnosis or condition

Etiology or clinical findings

Histologic features

Autoimmune hepatitis

Predominantly young or perimenopausal women. Hypergammaglobulinemia, high titers of antinuclear, anti smooth muscle, and antiLKM antibodies.

Wilson disease

Usually in children or young adults Fulminant form accompanied with nonimmune hemolytic anemia. Predictable or direct hepatotoxins and drugs, eg, carbon tetrachloride, trichloroethylen, tetrachloroethane, mushroom (Amanita phalloides), and acetaminophen

Interface hepatitis, rosette formation, severe lobular inflammation with confluent and bridging necrosis. Broad areas of collapse surrounding regenerative nodules. Prominent plasma cell infiltrate. Massive hepatic necrosis with small regenerative nodules, cholestasis. Copper stain and quantitative hepatic tissue copper are helpful. Eosinophilic hepatocytes with coagulative necrosis in perivenular areas in early cases. Centrilobular collapse with numerous brown pigment-laden macrophages in surviving patients. Fat globules in surviving hepatocytes. Coagulative necrosis of perivenular hepatocytes. In patients with right sided heart failure, sinusoidal dilatation and congestion may obscure necrotic hepatocytes. Ballooning hepatocytes, Mallory bodies with neutrophils in perivenular areas. Central hyalin sclerosis. Steatosis is often present. Mild centrilobular canalicular cholestasis without hepatocellular damage or portal inflammation.

Toxic necrosis

Shock liver

Heart failure or shock after trauma, surgery, burns, hemorrhage, or sepsis.

Alcoholic hepatitis

History of alcohol abuse. Leukocytosis and fever. AST/ALT ratio ⬎ 1.

Intrahepatic cholestasis of pregnancy

Last trimester of pregnancy. Mild to severe jaundice with normal to slightly elevated aminotransferase. Between 31st and 38th weeks of pregnancy.

Acute fatty liver of pregnancy

Toxemia of pregnancy (HELLP syndrome)

Between 20th and 40th weeks of pregnancy

Sepsis

Bacterial toxins and hepatic hypoperfusion cause abnormal liver profile.

Surgery associated changes

Seen in surgical liver biopsy specimens obtained at the end of long operation.

Large bile duct obstruction

Gallstones, bile duct strictures, cholangiocarcinoma, or carcinoma of the head of pancreas.

of pregnancy (HELLP syndrome); however, viral hepatitis should always be considered in the differential diagnoses of jaundice in pregnant women, as it remains the most common cause.

Chronic hepatitis Chronic hepatitis is a persistent and often progressive inflammation of the liver over 6 months that is characterized histologically by lymphocytic infiltration of the portal tracts

Microvesicular fat droplets in the cytoplasm of enlarged hepatocytes with central nuclei. Portal and lobular lymphoplasmacellular infiltrate and mild cholestasis may be present. Fibrin in periportal sinusoids and portal vessels. Small foci of periportal hepatocyte necrosis and hemorrhage with minimal inflammation. Confluent necrosis in severe cases. Canalicular cholestasis in perivenular areas, microvesicular steatosis, and minimal hepatocyte damage. Ductular reaction and ductular cholestasis in prolonged sepsis. Perivenular coagulative necrosis in septic shock. Small, tight clusters of neutrophils in subcapsular area and perivenular sinusoids, resembling microabscesses. Bile in hepatocytes, Kupffer cells, and bile canaliculi. Pale swollen hepatocytes with rarefied cytoplasm (feathery degeneration). Edematous portal tracts with prominent marginal ductular reaction accompanied by neutrophils.

together with varying degrees of parenchymal inflammation, hepatocellular injury, and fibrosis. The primary causes of chronic hepatitis are the hepatitis viruses (hepatitis virus B, C, and D), alcoholic liver disease, nonalcoholic steatohepatitis, and autoimmune hepatitis. Drug-induced injury and metabolic diseases, such as Wilson’s disease and alpha1-antitrypsin deficiency, are less frequent but no less important etiologies of chronic hepatitis. As with acute hepatitis, chronic hepatitis has a wide spectrum of clinical manifestations, ranging from asymptomatic infection to decompensated cirrhosis. Elevation of serum aminotransferase

140

Figure 5 Chronic hepatitis with interface hepatitis (arrow) (H&E, ⫻200).

activities is less marked than in acute hepatitis. Other clinical and biochemical findings are related to the underlying cause. Symptoms of liver failure and portal hypertension occur when chronic hepatitis has progressed to cirrhosis.

General histology of chronic hepatitis Chronic hepatitis primarily affects the portal tracts. Regardless of cause, chronic hepatitis is characterized by a combination of portal inflammation, interface hepatitis, lobular inflammation, spotty necrosis, and different degrees of fibrosis. The portal tracts are expanded by various degrees of fibrosis with or without the formation of fibrous septa and by inflammatory cells, primarily lymphocytes, with variable numbers of plasma cells. Macrophages and eosinophils may be found, but typically are a minor component of the infiltrate. Sometimes there is extensive ductular reaction with neutrophilic infiltration, which is usually concurrent with the severity of the interface hepatitis. True interface hepatitis is present in chronic hepatitis. It is characterized by extension of the inflammatory infiltrate from the portal tracts into the adjacent parenchyma and hepatocyte damage at the limiting plate or interface region (Figure 5). When interface hepatitis is severe, expansion of portal tracts and pericellular fibrosis, which often leads to the formation of hepatocyte rosettes, are seen. Another form of activity in chronic hepatitis involves inflammation and hepatocyte injury and death within the hepatic lobule, which, similar to acute hepatitis, ranges in severity from spotty to bridging necrosis to multilobular necrosis. Lobular disarray often seen in acute hepatitis is not a prominent feature in chronic hepatitis. Kupffer cells in these areas of spotty necrosis may contain phagocytosed cellular debris. Continued interface hepatitis and the resulting fibrosis at the limiting plate leads to stellate enlargement of the portal tracts (periportal fibrosis) and eventually links adjacent portal tracts. In the meantime, portal– central or central-to-central bridging fibrous

Seminars in Diagnostic Pathology, Vol 23, No 3/4 septa in chronic hepatitis generally develops following episodes of confluent or bridging necrosis, which involves perivenular necrosis. Formation of liver cell plates that are two or three cells thick, which is best observed on silver stains for reticulin, indicates hepatocyte regeneration. Many different systems for scoring necroinflammatory activity and fibrosis have been developed throughout the years mainly for chronic viral hepatitis and lately also for autoimmune hepatitis. The Knodell system, published in 1981, has served as a prototype for semiquantitative scoring of liver biopsy specimens.30 With modification, this system is still widely used, especially for therapeutic trials. Pathologic scoring systems, such as the METAVIR31 and Scheuer score32 and the Ishak Hepatitis Activity Index (HAI),33 are now commonly used. These systems use four or five categories for necroinflammatory activity and four to seven for stage of fibrosis (Figure 6). A pathology report should include clear verbal descriptions of the extent of fibrosis and severity of necroinflammatory activity; therefore, one can later transcribe a scoring system to another preferred scoring system. Regardless of which grading and staging system is to be used, it is best to communicate to the submitting clinicians which system is used. It is also important to realize that these systems are not to be regarded in the same fashion as biochemical laboratory tests; they were all created for purposes of comparison of biopsies in treatment trials and not for diagnostic purposes. In addition to stage and grade, accurate assessments of both steatosis and iron accumulation should be provided, which may reduce response to therapy in chronic viral hepatitis.

Chronic viral hepatitis Liver biopsy is rarely done in “healthy carriers” of hepatitis B virus (HBV) (now called “inactive HBsAg carriers”), ie, patients with anti-HBe antibodies, persistently normal aminotransferase levels, very low or undetectable

Figure 6 Chronic hepatitis with fibrous septum (stage 2) (Trichrome stain, ⫻200).

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Figure 7 Chronic hepatitis with HBsAg containing ground glass hepatocytes (arrows) (H&E, ⫻400).

Figure 9 Lymphoid follicles in a portal tract of a patient with chronic hepatitis C (H&E, ⫻200).

levels of serum HBV DNA, and normal ultrasonographic findings.34 Hepatitis B surface antigen (HBsAG)-positive ground glass hepatocytes are seen only in chronic and not in acute infection (Figure 7). These cells are filled HBsAg containing smooth endoplasmic reticulum, and are likely to be numerous in mildly active disease. Identification of cytoplasmic HBsAg can be facilitated by Shikata orcein or Victoria blue stains, or immunohistochemical stain. Hepatitis B core antigen (HBcAg) accumulation in hepatocyte nuclei produces “sanded” nuclei. HBcAg can be better visualized by immunohistochemical stain. Cytoplasmic and membranous HBcAg positivity indicates high levels of viral replication (Figure 8). Active disease on liver biopsy is useful information in planning management, since it predicts a better response to any of the currently available drugs (interferon, nucleoside analogues). The morphology of hepatitis B with D virus coinfection resembles that of B infection alone, but the necroinflammatory activity is often

more severe.9 In combined B and D virus infection, sanded nuclei may also be seen, and HDAg may be demonstrated by immunohistochemical stain. Chronic hepatitis caused by hepatitis C virus (HCV) tends to be mild. Characteristic features of HCV infection include dense portal lymphocytic infiltrates, often with lymphoid aggregates and sometimes with follicle formation, accompanied by varying degrees of interface hepatitis; mild degrees of biliary epithelium damage (the “Poulsen lesion”) and steatosis in up to 70% (Figure 9).10 The latter is usually macrovesicular and focal. Nonnecrotizing granulomas may be rarely seen, but other concurrent causes of granulomas must be excluded. Immunohistochemical stain for HCV has been reported, but its use has not been proven reliable. The progression of chronic viral hepatitis to advanced fibrosis/ cirrhosis may be related to virus genotype, host profile, and other factors. For instance, HCV genotype 1 is associated with more severe disease than genotype 2, necroinflammatory activity usually correlates with serum HCV RNA levels, and steatosis is more commonly seen in genotype 3b.35–37 Hepatitis C may induce autoantibody formation such as anti-LKM type 1, but the titers are low. Clinically, these patients still resemble patients with chronic hepatitis C and not those with autoimmune hepatitis. The presence of severe activity and a significant number of plasma cells in the area of interface hepatitis in a liver biopsy specimen of a patient with chronic hepatitis C suggests concurrent autoimmune features, which are either induced by the HCV infection or by the treatment with interferon. The overlap syndrome of autoimmune hepatitis and chronic hepatitis C implies the coexistence of autoimmune hepatitis with high titer of autoantibodies and high IgG level, and detectable HCV RNA. The diagnosis of autoimmune hepatitis alone should never be rendered to patients that are known to harbor the virus (detectable HCV RNA), since corticosteroid therapy will enhance viral replication and disease progression. Hepatitis B and C coinfection is not rare. In some, the recently acquired virus suppresses the replication of the

Figure 8 HBcAg in nuclei and cytoplasm of hepatocytes in a patient with chronic HBV infection with active viral replication (Immunostain, ⫻400).

142 preexisting virus. If there is coreplication of both viruses, the liver disease is likely to be more active and shows faster progression. Although the histological features of hepatitis C are often predominant in dual infections, immunostaining for HBV antigens are particularly helpful in determining the predominant virus causing liver injury.38 Extensive HBcAg staining in nuclei and cytoplasm of hepatocytes indicates high HBV replication and corresponds to high hepatitis B disease activity, whereas the absence of or low HBcAg expression suggests the predominant role of HCV in the hepatitis activity. Hepatitis virus and human immunodeficiency virus (HIV) coinfection are frequently encountered. The impact of HIV on chronic hepatitis B or C includes higher viral load, higher prevalence of fibrosis/cirrhosis, and rapid progression of the fibrosis.39 Fibrosing cholestatic hepatitis (FCH), which is an atypical pattern of hepatitis B liver injury, may be encountered in these immunosuppressed patients.40 FCH is a rapidly progressive disease with severe parenchymal damage, extensive fibrosis, and mild inflammatory reaction. The parenchymal changes are characterized by marked hepatocyte swelling and cholestasis with minimal lobular inflammation. It is accompanied by marked ductular reaction at the limiting plate, which is often combined with cholangiolitis and extensive periportal sinusoidal fibrosis. Well-developed cirrhosis, however, does not develop. The extremely high levels of HBV replication and the massive HBcAg expression in the liver, in addition to the nonsignificant inflammatory component, suggest a direct cytopathic effect of HBV. Lastly, the potential of hepatotoxicity of antiretroviral treatment in the setting of coinfection should not be overlooked.

Autoimmune hepatitis Autoimmune hepatitis (AIH) is a syndrome characterized by chronic hepatitis in association with polyclonal hypergammaglobulinemia, immunogenetic predisposition (HLA-B8, -DR3, or -DR4), high titers of circulating autoantibodies (⬎1:80), negative viral hepatitis profiles, and favorable response to immunosuppressive therapy.41 AIH predominantly affects young and middle-aged women. AIH is considered a chronic disease; however, its onset may be acute, clinically mimicking acute viral hepatitis. Patients present with fatigue, jaundice, hepatosplenomegaly, and sometimes signs of chronic liver disease. Associated autoimmune disorders such as Hashimoto’s thyroiditis, hemolytic anemia, migrating polyarthritis, and others may be present. Based on the autoantibody profiles, two principal types of AIH are recognized: type 1 with high serum titers of antinuclear antibodies (ANA) with or without smooth muscle antibodies (SMA), and type 2 with liver– kidney microsomal antibodies (LKM1). The combination of clinical and laboratory findings of AIH have been incorporated by the International Autoimmune Hepatitis Group into a scoring system, the sum of which describes the probability of the diagnosis of AIH.41 Knowledge of these parameters

Seminars in Diagnostic Pathology, Vol 23, No 3/4 during interpretation of diagnostic liver sample can be extremely helpful (Table 3). Autoimmune hepatitis before treatment generally shows histologic changes of chronic hepatitis with disease activity, which in most cases is more severe than in hepatitis B or C. Occasional lymphoid aggregates or follicles may be seen in portal tracts. Numerous plasma cells are seen in clusters within the portal, periportal, and in the lobules. Interface hepatitis and septal fibrosis involve all portal tracts, often with rosette formation of periportal hepatocytes. Syncytial giant hepatocytes are seen in minority of patients. Perivenular necrosis, bridging, and confluent necrosis leading to broad areas of parenchymal collapse; and large, irregular, regenerative nodules are often seen (Figure 10). Cirrhosis develops rapidly and early. The histologic differential diagnosis of AIH often depends on its clinical presentation. In cases presenting as severe acute hepatitis, the differential diagnoses include drug-induced injury and viral hepatitis; whereas in cases with chronic disease, the differential diagnoses are even broader to include alcoholic and nonalcoholic steatohepatitis and chronic biliary diseases. Histological remission of AIH is defined as the absence of interface hepatitis. Relapse is common after immunosuppressive treatment withdrawal. AIH can “overlap” with primary biliary cirrhosis and rarely with primary sclerosing cholangitis. The latter is more common among children with autoimmune liver disease.42 The hepatitic and biliary disease component should be evident histologically for the diagnosis of overlap syndrome to be considered. Because the treatment of AIH differs from chronic biliary diseases, overlap syndromes may cause therapeutic dilemmas and treatment should be tailored individually. The overlap syndrome of autoimmune hepatitis and chronic viral hepatitis implies the coexistence of autoimmune hepatitis with high titers of SMA or ANA, hypergammaglobulinemia, and concurrent immune diseases with a true viral infection (most commonly chronic hepatitis C). Since treatments of AIH and viral hepatitis contradict the other, the histological examination becomes important in directing treatment against the predominant disease.

Drug-induced chronic hepatitis Drugs are responsible for less than 1% of cases of chronic hepatitis and cirrhosis.43 Liver disease usually develops more than a year after therapy has been started. The spectrum of clinical symptoms varies and ranges from asymptomatic elevation of aminotransferase activities to cirrhosis. Chronic drug-induced hepatitis often mimics chronic hepatitis of other causes, both clinically and morphologically. Complete serologic tests to eliminate viral and autoimmune hepatitis and critical chronologic history of drug intake are crucial. Regardless of these, difficulties often remain in the definitive diagnosis of chronic druginduced liver disease. The separation is especially difficult from AIH, because drug-induced hepatitis often resembles AIH, and the drug may also trigger autoimmunity. Based on

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Autoimmune hepatitis scoring system41

Feature Sex Alk phos:ALT or Alk phos: AST (IU/L) above normal limits Serum globulins or IgG above normal ANA, SMA, or LKM1

Score in parentheses Male (0) 1.5-3.0 (0)

⬎3 (⫺2)

Female (2)

⬍1.5 (2)

⬍1 ⫻ normal (0)

1-1.5 ⫻ normal (1)

1.5-2 ⫻ normal (2)

⬎2 ⫻ normal (3)

⬍1:40 (0)

1:40 (1)

1:80 (2)

⬎1:80 (3)

AMA

Positive (⫺4)

Negative (0)

Hepatitis viral markers

Positive (⫺4)

Negative (3)

Drug history

Yes (⫺4)

No (1)

Average alcohol intake (gm/day) Histology

⬎60 (⫺2)

⬍25 (2)

Absence of all of the following: interface hepatitis, lymphoplasmacytic infiltrate, and liver cell rosettes (⫺5)

Biliary changes or other defined changes (⫺3 each)

Predominantly lymphoplasmacytic infiltrate, liver cell rosettes (1 each)

Interface hepatitis (3)

Other autoimmune disease (patient or first degree relatives)

Absent (0)

Present (2)

Seropositivity for other defined autoantibodies

Absent (0)

Present (2)

HLA DR3 or DR4

Absent (0)

Present (1)

Response to therapy

Complete (2)

Relapse (3)

Total Score

Interpretation

⬎15 prior to therapy

Definite autoimmune hepatitis

10-15 prior to therapy

Probable autoimmune hepatitis

⬎17 following therapy

Definite autoimmune hepatitis

12-17 following therapy

Probable autoimmune hepatitis

this feature, drug-induced chronic hepatitis can be subdivided into several categories (Table 4), including those with features resembling AIH type 1 and type 2, clinically and histologically.44

Alcoholic liver disease The development of alcoholic liver disease results from the chronic and excessive consumption of alcoholic beverages. There is a wide spectrum of histology for alcoholic liver disease that includes that of fatty liver disease, alcoholic hepatitis (without steatosis), alcoholic foamy degeneration, cholestasis, veno-occlusive disease, sclerosing hyaline necrosis, and micronodular cirrhosis.45,46 Histologically, alcoholic steatohepatitis is characterized by swollen hepatocytes with pale or clear cytoplasm, so-

Figure 10 Autoimmune hepatitis with severe interface hepatitis (arrow) and centrilobular necrosis (arrowheads) (H&E, ⫻100).

144 Table 4

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Drugs

Comments

Syndrome resembling autoimmune hepatitis type 1 Clometacine ASMA, Anti-DNA Methyldopa ANA, ASMA Minocycline ANA, Anti-DNA Nitrofurantoin ANA, ASMA Oxyphenisatin ANA, ASMA Benzarone ANA Diclofenac ANA Ecstasy ANA Fenofibrate ANA Papaverine ANA, ASMA Propylthiouracil ANA Syndrome resembling autoimmune hepatitis type 2 Dihydralazine Anti-CYP1A2 Halothane Anti-carboxylesterase, anti disulfide isomerase. Iproniazid Anti- microsomal antibody-6 Syndrome with histology of chronic hepatitis Lisinopril Sulphonamide Trazadone Syndrome of chronic toxicity Acetaminophen Aspirin Isoniazid Steatosis Valproic acid Methotrexate Tetracycline Phospholipidosis Perhexiline maleate Amiodarone

Microvesicular steatosis Macrovesicular steatosis, fibrosis Microvesicular steatosis Enlarged foamy or granular hepatocytes, Mallory hyalines; lamellated lysosomes under electron microscope.

Nonalcoholic steatohepatitis Diethylstilbesterol Corticosteroids Nifedipine Tamoxifen Didanosine ASMA, anti-smooth antibodies.

muscle

antibodies;

ANA,

Figure 11 Hepatocytes containing Mallory’s hyalins in a patient with severe alcoholic hepatitis who had stopped drinking 6 months earlier (H&E, ⫻400).

with ductular reaction and wide fibrous septa linking adjacent terminal hepatic venules are seen (Figure 12). Siderosis in hepatocytes is sometimes seen in alcoholics, but is usually minimal and often is accompanied by hemosiderin in Kupffer cells. Fibrosis is a common feature of alcoholic hepatitis with its most characteristic perisinusoidal or pericellular form, so-called “chicken wire” type of fibrosis. Involvement of terminal hepatic venules results in thickening of the walls and narrowing and occlusion of their lumens. Lesions other than alcoholic hepatitis may contribute to the fibrosis or cirrhosis in the alcoholics. Studies have found that alcoholic patients have a higher incidence of chronic hepatitis B or C infection.47 Therefore, the presence of prominent lymphoid aggregates or follicles with or without interface hepatitis, lobular inflammation, or scattered acidophilic bodies should raise the suspicion of confounding chronic viral hepatitis.

anti-nuclear

called ballooning degeneration. Focal necroses are also present. The ballooned hepatocytes often contain alcoholic hyalin in the cytoplasm and are surrounded by neutrophils (“satellitosis”). Mallory hyalin or alcoholic hyalin represents clumps or strands of intermediate filaments of the cytoskeleton, which are positive for cytokeratins 8 and 18, ubiquitin, and p62 (Figure 11). Giant mitochondria in the cytoplasm of hepatocytes are seen occasionally as globular or spindle shaped inclusions measuring 2 to 10 ␮m across. The significance of megamitochondria is unknown. In early stages, distribution of the inflammation is near the terminal hepatic venules. In more severe cases, bridging necrosis

Figure 12 Chronic alcoholic liver disease with severe central hyaline sclerosis. Cholestasis and steaosis is also seen (H&E, ⫻200).

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Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis Nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH) are increasingly recognized as common liver disorders. The former, which affects approximately one-fourth of the US population and up to twothirds of obese people, is believed to have a benign course in most, but not all individuals, and represents a manifestation of a systemic metabolic state. The latter, NASH, is a progressive form of liver injury that carries a risk for progressive fibrosis, and cirrhosis; it may also carry a risk of hepatocellular carcinoma and is recognized as a factor for end stage liver disease. Most patients with NASH have “metabolic syndrome,” ie, hypertension, insulin resistance, obesity, and dyslipidemia. The role of insulin resistance in NASH has been confirmed, and the multifaceted functions of visceral adipose tissue that link obesity, insulin resistance, hepatic steatosis, and fibrosis continue to be elucidated. Metabolic syndrome and hyperinsulinemia require proper therapy, including optimal diabetic management and weight reduction. The diagnoses of NAFLD and NASH remain ones of clinicopathologic correlation. Liver biopsy has retained its role in the clinical diagnosis or confirmation of NASH. Moreover, histological evaluation remains the only means of accurately assessing the degree of steatosis and activity, the distinct necroinflammatory lesions and fibrosis of NASH, and in distinguishing NASH from “simple” steatosis.48 Further, evaluation of liver biopsy serves to confirm the diagnosis and/or exclude other possible causes of liver test elevation in the phenotypically predisposed patient. The lesions of NAFLD and NASH share some features of alcoholic liver disease, but are not necessarily identical to alcoholic liver disease as previously stated in the literature. In general, NASH commonly resembles mild alcoholic hepatitis48; therefore, histological evaluation often cannot reliably distinguish NASH and mild alcoholic steatohepatitis. In this regard, it has been suggested to pathologists to discontinue the use of the “nonalcoholic,” and the diagnosis should reflect the presence of microscopic lesions and pattern and extent of injury (steatohepatitis and fibrosis), and a clinical association if provided (ie, diabetes, obesity). Some authors consider that there may be more fat globules, and less hepatocellular damage, Mallory hyalin, inflammation, and fibrosis in NASH compared with alcoholic hepatitis,49 but these are not useful criteria on an individual patient basis. Central hyalin sclerosis with cholestasis is yet to be described in NASH. Steatosis varies from mild to severe and is mainly macrovesicular and concentrated in centrilobular areas. The minimum quantity of hepatocytes involved is not set. Small amounts of steatosis may be present in otherwise healthy individuals. It is accepted that, in adults, more than 5% to 10% steatotic hepatocytes in centrilobular distribution, accompanied by hepatocyte ballooning and inflamma-

145 tion, define NASH. Mallory hyalin may or may not be present. Most pathologists consider hepatocyte ballooning as the required feature of NASH in adults.48 Lobular inflammation is usually mild, often with neutrophils. Abundant Mallory hyalin suggests alcoholic hepatitis.50 Additional findings that may be noted are glycogenated nuclei in periportal hepatocytes, lipogranulomas, scattered megamitochondria in hepatocytes, and fat cysts. As described above for ALD, the characteristic fibrosis in NASH is the initial deposition of collagen in perisinusoidal spaces in acinar zone 3. With progression of fibrosis, fibrous septa, bridging fibrosis, and eventually cirrhosis develop. Perisinusoidal fibrosis may no longer be seen with extensive bridging fibrosis, cirrhosis, and architectural remodeling of the parenchyma.48 The presence of perisinusoidal fibrosis in the absence of active inflammation may indicate previous episodes of steatohepatitis. Although the main process in NASH is located in acinar zone 3 (centrilobular), some degree of portal and periportal fibrosis can also be seen in adults and is more pronounced in the pediatric population. There are differences in NASH features in children, for example, more severe steatosis, minimal or no hepatocyte ballooning or Mallory’s hyalins, less lobular inflammation, minimal or no neutrophils, and more portal chronic inflammation. Consequently, portal fibrosis without concomitant perisinusoidal fibrosis is commonly observed.51 Grading and staging system for NASH has been developed to provide a standardized method of semiquantitative activity of the lesions and the pattern of fibrosis. A proposed aggregate grading for NASH by Brunt and coworkers52 has been well adopted among pathologists. This system use three categories for activity of disease (mild, moderate, and severe) and four for stage of fibrosis, based on the paradigm of zone 3 perisinusoidal fibrosis as described above. More recently, the Pathology Committee of NASH Clinical Research Network designed and validated a feature-based scoring system that is a modification of the Brunt system that also addresses the full spectrum of lesions of NAFLD.53 The total activity score represents the sum of individual scores for steatosis, lobular inflammation, and ballooning, and ranges from 0 to 8. The fibrosis stages (0-4) are similar to those proposed by Brunt and coworkers, with fine separations of stage 1 to reflect mild and moderate perisinusoidal fibrosis, as well as the portal-only fibrosis in pediatric NAFLD. The authors emphasized that, even though the higher scores correlated with diagnostic evaluations of steatohepatitis, the scores in and of themselves were not meant as replacements of diagnostic considerations by the pathologists, but rather as standardized semiquantitative values for which therapeutic trials could be assessed. As in grading and staging of chronic viral hepatitis, regardless of which grading and staging system is to be used, it is best to be communicated to the submitting clinicians.

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Metabolic diseases and other causes of chronic hepatitis Wilson disease is an autosomal recessive disorder of copper transport that causes chronic liver disease and may progress to fulminant hepatic failure or to cirrhosis. The gene that is involved is designated as ATP7B on chromosome 13, which encodes transmembrane coppertransporting ATPase.54 The chronic form of Wilson disease begins between the ages of 3 and 50 years, and like chronic hepatitis, may be asymptomatic or cause mild fatigability and malaise. The diagnosis should be considered in any patient with unknown hepatocellular disease after 5 years of age. Kayser–Fleischer rings and neuropsychiatric symptoms, particularly in young adults, are highly suggestive of the diagnosis. A nonimmune hemoTable 5

lytic anemia is commonly seen when the presentation is that of acute liver failure. Morphologic changes in early Wilson disease may be mild and often resembles steatohepatitis. Moderate to severe steatosis is common, accompanied by mild lobular necroinflammatory activity and glycogenated nuclei in periportal hepatocytes. As the disease progresses, the livers of the patients show steatosis, extensive or diffuse ballooning of hepatocytes, the presence of Mallory hyalin and apoptotic bodies, cholestasis, and mild inflammation. In contrast to the perivenular location of Mallory hyalin in alcoholic hepatitis or NASH, Mallory hyalin in Wilson disease seems to be more diffusely distributed throughout the lobule. Periportal fibrosis, bridging fibrosis, and eventually cirrhosis develop. Changes indistinguishable from autoimmune hepatitis have been reported, especially in children.55

Differential diagnoses and conditions mimicking chronic hepatitis

Diagnosis or condition

Etiology or clinical findings

Histologic features

Liver capsule and subcapsular liver parenchyma

Surgical biopsies taken from the inferior edge of the liver or the immediate 2-mm subcapsular parenchyma. Percutaneous biopsy.

Primary sclerosing cholangitis

Often with history of inflammatory bowel disease. Abnormal cholangiography.

Primary biliary cirrhosis

Associated with Sjogren’s and CREST syndromes. AMA positive, high IgM.

Lymphoma

As part of workup in patients with lymphoma, or unknown low grade lymphoma with elevated liver tests, or liver mass in high grade lymphoma.

Chronic passive congestion

Chronic heart failure

Nodular regenerative hyperplasia

Portal hypertension and enlarged liver. Clinically confused with cirrhosis. Associated with autoimmune disorders and elevated canalicular enzymes.

Increased fibrous tissue. Liver capsule may be seen in percutaneous liver biopsies at one end of the specimen or in the form of separate pieces of connective tissue and can be distinguished from most pathological fibrous tissue by its density and maturity and often contain blood vessels and bile ducts. Bile duct loss, periductal sclerosis, lymphocytic cholangitis, ductular reaction. Bile duct loss and damage, florid duct lesion, portal epithelioid granulomas. Expansive dense monomorphic portal infiltrate compressing adjacent hepatocytes and sinusoidal infiltration without hepatocyte damage in low grade lymphoma Epithelioid granulomas in Hodgkin’s disease. Dilatation, congestion and fibrosis of perivenular sinusoids with compression of hepatocytes. Lipofuscinosis, fat globules and sometimes bile pigments may be seen in the compressed hepatocytes. Small nodules separated by linear areas of atrophic hepatocytes and congested sinusoids, with no or minimal fibrosis. Hyperplastic hepatocytes in more than two cell thick plates form the nodules. Obliteration of small portal vein often seen. Reticulin stain is helpful.

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Copper can be visualized using rhodanine stain. In the precirrhotic stage, stainable copper is confined to periportal hepatocytes, whereas in the cirrhotic liver, the distribution of copper is irregular, with some cirrhotic nodules containing a lot and others containing little or none.56 Serum ceruloplasmin below 20 mg/dL, 24-hour urine copper excretion greater than 100 ␮g, and quantitative liver copper concentration over 250 ␮g/gm are necessary for definitive diagnosis. Alpha-1-antitrypsin (A1AT) deficiency is an autosomal recessive disorder leading to accumulation of alpha-1-antitrypsin in periportal hepatocytes, as eosinophilic, PAS-positive, diastase-resistant globular inclusions. The presence of A1AT in the inclusions can be confirmed by immunohistochemical stain. The involved gene is located on chromosome 14q and most commonly caused by homozygosity for the PIZ allele. The A1AT globules increase in number and size with age, and may be inconspicuous in children.57 In adults, the histologic changes are those of chronic hepatitis with varying degrees of fibrosis and cirrhosis, but inflammation is rarely a prominent feature. In infants, the common presentation is cholestatic liver disease, with morphologic changes of neonatal hepatitis, ie, canalicular cholestasis, giant cell hepatocytes, and ballooning degeneration of hepatocyte; or with ductular reaction and varying degree of fibrosis or cirrhosis. Therefore, alpha-1-antitrypsin deficiency should be included in the differential diagnosis of neonatal cholestasis and extrahepatic biliary atresia in infants.58

Differential diagnosis and conditions mimicking chronic hepatitis Any liver disease with portal lymphoplasmacytic infiltrate and fibrosis may resemble chronic hepatitis and should be considered in its differential diagnosis. Some of the most common conditions that may mimic chronic hepatitis are listed in Table 5.

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