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Solitary hepatic cysts
Collective Reviews
Solitary Hepatic Cysts Robert A Cowles, MD, Michael W Mulholland, MD, PhD, FACS
techniques have generated new information on the incidence of liver cysts. In 1989, a European study reported the incidence of simple hepatic cysts in 1,695 patients who had been referred for abdominal or pelvic ultrasonography. In this population, the overall incidence of liver cysts was 2.5%, with a sharp increase in incidence noted in individuals more than 60 years of age.4 A separate European study reported the incidence of liver cysts in more than 26,000 patients undergoing upper abdominal ultrasonography. A total of 1,235 liver cysts were identified for a calculated incidence of 4.75%. In this study, 61.2% of cysts were classified as simple hepatic cysts resulting in an incidence of simple cysts of 2.8%.5 More than 92% of cysts identified in this latter study were in patients more than 40 years of age.5 Hepatic cysts are encountered more often in female patients. The female to male ratio is estimated to be 1.5:16 and cysts are symptomatic more often in women than in men.7 The pathogenesis of hepatic cysts is unclear, but likely related to the type of cyst. Solitary benign nonparasitic cysts are believed to be congenital. Solitary benign cysts are lined by cuboidal epithelium and are thought to arise from abnormal development of intrahepatic bile ducts in utero. These collections of aberrant ducts enlarge slowly and only result in symptoms later in life. In contrast, neoplastic and traumatic cysts are acquired. Cystic neoplasms of the liver include benign biliary cystadenomas and the malignant variant, the biliary cystadenocarcinoma. The cause of cystic neoplasms is unknown. Traumatic cysts are acquired and occur from continued bile leakage from an injured intrahepatic bile duct after abdominal trauma.
The treatment of liver cysts continues to evolve in terms of diagnosis and surgical therapy. In the past, hepatic cysts were usually discovered at laparotomy, but they have become an increasingly common incidental finding on radiographic studies such as ultrasonography and CT scan. Occasionally liver cysts present as symptomatic abdominal masses. Hepatic cysts can be divided into two general categories: congenital and acquired (Table 1). Because the cause and treatment of cystic lesions of the liver differ, depending on the lesion and on the presence or absence of symptoms, it is important to be familiar with the appropriate evaluation and management of these masses. This article reviews common presentations, diagnostic methods, and treatment of congenital and acquired liver cysts. Discussion of infectious cysts, including amoebic, pyogenic, and hydatid cysts, and complex multicystic liver disease, has been excluded from this review. INCIDENCE AND PATHOGENESIS Hepatic cysts are noted frequently as incidental findings at laparotomy, but determining the precise incidence of hepatic cysts is difficult. Early estimates of the incidence of liver cysts were generated from autopsy studies. In a report of 20,000 autopsies, 28 hepatic cysts were found, for a calculated incidence of 0.14%.1 Other early series reported similarly low incidences of 0.17% and 0.53%.2,3 More recently, improvements in radiographic technology and increased use of abdominal imaging Received April 20, 2000; Accepted May 24, 2000. From the Section of General Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI. Correspondence address: Michael W Mulholland, MD, PhD, FACS, Department of Surgery, 2920B Taubman Center, Box 0331, 1500 East Medical Center Dr, Ann Arbor, MI 48109-0331. © 2000 by the American College of Surgeons Published by Elsevier Science Inc.
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Table 1. Categories of Cystic Liver Disease Congenital
Acquired
Solitary benign nonparasitic cysts Polycystic liver disease Caroli’s disease
Neoplastic cysts Traumatic cysts Infectious cysts
PRESENTATION The presentation of patients with hepatic cysts is variable and dependent on the type of cyst. Most cysts are asymptomatic, with the liver lesion noted during ultrasonography or on CT scan performed for an unrelated reason. Several studies suggest that patients with nonparasitic and neoplastic cysts most commonly present after age 50 and are more likely female. Trauma is common in younger individuals, so the population of patients with traumatic cysts is younger than the population with simple congenital cysts. Symptoms and physical examination Only a small fraction of nonparasitic cysts are symptomatic. An extended experience at the Mayo Clinic between 1907 and 1971 revealed that only 24% of simple cysts (27 of 120) were symptomatic.2,8 Symptoms were more commonly present in patients with neoplastic and traumatic cysts, although these cysts were encountered with much lower frequency. Although hepatic cysts usually become symptomatic in the fourth or fifth decades of life, cases involving children and young adults have been reported.9-12 Symptoms attributed to liver cysts are listed in Table 2. Abdominal pain and abdominal mass are the most frequently noted complaints and are present in more than 50% of patients. Other less common complaints include nausea, vomiting, early satiety, fatigue, and jaundice.11,13-15 Symptoms usually result from mass effect caused by the enlarging cyst. Some patients complain of dull, aching pain and others have seTable 2. Common Symptoms Attributed to Liver Cysts Symptom
Frequency (%)
Abdominal pain: chronic, dull or acute, severe Abdominal mass Jaundice Early satiety, nausea, vomiting
50–93 25–53 7–13 20–42
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vere sharp, episodic pain requiring narcotic analgesics for relief. Making an immediate distinction between simple, neoplastic, and traumatic cysts is difficult although an antecedent history of abdominal trauma or an earlier history of simple cyst can be a clue to the diagnosis. Physical examination may reveal a palpable abdominal mass or hepatomegaly, but these findings are nonspecific and are not sufficient to secure a definitive diagnosis. DIAGNOSTIC EVALUATION Imaging studies Because most hepatic cysts are either asymptomatic or produce only mild, nonspecific symptoms, and because they are difficult to evaluate by physical examination, imaging studies are of paramount importance to the physician caring for affected patients. In many instances, imaging studies are the means by which these lesions are initially discovered. The improvement in abdominal imaging techniques during the past two decades has greatly facilitated the diagnosis of abdominal pathology including hepatic cysts. Ultrasonography, CT scan, and less frequently, MRI studies are used to classify and anatomically delineate cystic hepatic lesions. Although simple hepatic cysts and traumatic cysts are distinct clinical entities, their appearance on imaging studies is often similar and the radiographic descriptions within this review pertain to both types of cysts. The distinction between simple or traumatic cysts and neoplastic cysts is most important and will be stressed. Ultrasonography is an inexpensive, simple, and noninvasive technique for evaluation of liver cysts. Ultrasonography is considered to be the most accurate imaging modality for the diagnosis of hepatic cysts with sensitivity and specificity of greater than 90%.16,17 Ultrasonography is recommended as an initial diagnostic modality, because when compared with CT scan and MRI, it is easy to perform, portable, and provides considerable diagnostic information about lesions in the liver.18-20 On ultrasonographic examination, liver cysts appear as anechoic masses with smooth margins and a thin, imperceptible wall (Fig. 1).17,19,21 Back wall enhancement is generally seen because of differential reflection of sound waves by the cyst fluid and the posterior wall
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Figure 1. (A) Abdominal ultrasound performed for evaluation of right upper quadrant pain. The study reveals a small anechoic round lesion with a thin wall diagnostic for liver cyst (arrow). (B) Abdominal ultrasound in this patient revealed a larger simple hepatic cyst within the substance of the liver. (C) Ultrasound appearance of a large simple hepatic cyst. The interface between the cyst and the liver parenchyma is seen (arrowheads). This cyst was symptomatic and measured 15 cm in greatest dimension.
of the cyst with its surrounding liver parenchyma (Fig. 1).19 Ultrasonography allows distinction between cystic and solid lesions within the liver. When ultrasonography reveals a cystic structure, it can also help to differentiate types of cysts. Although all hepatic cysts are anechoic on ultrasound, biliary cystadenomas can be differentiated from
simple or traumatic cysts based on the internal ultrasonographic anatomy. In contrast to simple cysts, which are unilocular, biliary cystadenomas have a septated, multilocular appearance on ultrasound. The presence of septae should suggest the diagnosis of neoplastic cyst.21 The presence of debris within the cyst cavity by ultrasonography is
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Figure 2. (A) Contrast-enhanced abdominal CT scan performed for staging of a pancreatic carcinoma. This imaging study incidentally revealed a small, asymptomatic simple hepatic cyst in the left lobe of the liver (arrow). Note the water density of the cyst cavity and the thin, imperceptible wall. (B) Contrast-enhanced abdominal CT scan revealing a large centrally located simple liver cyst.
suggestive of malignancy and should prompt the clinician to pursue further investigation.22 Ultrasonography is also able to provide additional information when jaundice is present. In this scenario, ultrasonography can be used to evaluate the biliary tree for intra- and extrahepatic biliary dilatation secondary to mass effect caused by a large liver cyst. Abdominal CT scan is used to delineate lesions
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in the liver. Although ultrasound examination can define whether a liver lesion is solid or cystic and can suggest a diagnosis of hepatic cyst, CT scan is superior in determining the location and spatial relationships between liver cysts and surrounding structures such as blood vessels, bile ducts, and hollow viscera. For these spatial relations to be appreciated, abdominal CT scans should be performed with oral and intravenous contrast. The infusion of intravenous contrast should be carefully timed and should occur with a short delay before initiation of scanning.23 This protocol will allow the liver to be scanned during the time of maximal hepatic contrast enhancement.23 On CT scan, hepatic cysts are nonenhancing, fluid (ie, water) density lesions with a thin, uniform wall (Fig. 2). When liver cysts are small (⬍1cm) the CT and ultrasound-based diagnosis of benign cyst can be more difficult and generally requires repeat imaging studies for followup if clinically indicated.23 When water density cystic structures seen on abdominal CT scan are septated and multilocular or when papillary projections are present within the cyst, the diagnoses of cystadenoma or cystadenocarcinoma should be considered (Fig. 3). MRI scanning is rarely the initial imaging modality for diagnosis of hepatic cysts. Knowledge of MRI characteristics is useful when cystic structures are identified on MRI done for another reason. When seen on MRI, simple hepatic cysts are wellcircumscribed lesions that are very hypointense on T1-weighted images and hyperintense on T2weighted images24 (Fig. 4). If there has been hemorrhage into a hepatic cyst, this appearance changes and the cyst becomes hyperintense on both T1- and T2-weighted images. Descriptions of the MRI appearance of biliary cystadenomas and cystadenocarcinomas are limited, but the multilocular nature of this lesion is evident on MRI (Fig. 5). Unfortunately, even MRI imaging techniques cannot accurately distinguish whether these neoplasms are benign or malignant. Additional imaging modalities are occasionally useful. Plain x-rays or upper gastrointestinal contrast studies may reveal elevation of the right hemidiaphragm or compression of normal intraabdominal structures.25 Liver scintiscans are consistent with a “cold” cyst. Angiography will reveal the cyst as an
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avascular mass with stretching or displacement of surrounding vessels and perhaps causing mass effect.26 These studies are rarely necessary and are not generally helpful if ultrasonography, CT scan, or both have previously been performed. Laboratory evaluation in patients with liver cysts should be tailored to the underlying condition, age, and findings on physical examination. Routine laboratory values including liver function tests are normal and most studies have reported no significant abnormality in any laboratory parameter.11,27 On rare occasions, elevations in bilirubin will be noted, from biliary obstruction caused by a large cyst. Ecchinococcal serology should be obtained in all patients with cystic lesions of the liver. TREATMENT The treatment of cystic liver masses depends on factors ascertained preoperatively: the presence or absence of symptoms and the appearance of the cyst on ultrasound or CT scan.
Figure 3. Abdominal CT scan performed for right upper quadrant abdominal pain. A biliary cystadenoma is seen with characteristic internal septations. This lesion was confirmed to be a cystadenoma at laparotomy.
Simple cysts Successful treatment of simple hepatic cysts begins with a focused history and physical examination. The physician should specifically seek to elicit a history of abdominal pain or increasing abdominal girth. The abdomen should be carefully examined for the presence of masses or hepatomegaly. Often, the operative or radiographic discovery of these liver lesions occurs incidentally and questions regarding abdominal symptomatology are asked in retrospect. When simple hepatic cysts are found incidentally by abdominal imaging and are determined to be asymptomatic, conservative management is appropriate.28,29 Likewise, simple hepatic cysts encountered incidentally at laparotomy should be treated conservatively. This expectant approach is based on the observation that a large majority (80% to 95%) of liver cysts remain asymptomatic.2,6 In addition, when symptoms related to a cyst do occur, treatment can be instituted with low morbidity and virtually no mortality. On occasion, an intraoperatively encountered cyst is pedunculated, and easily excised. These pedunculated cysts are thought to be at risk for torsion, and if possible, a simple cyst resection has been recommended.25,28 When a cyst is encountered during an abdominal exploration and the diagnosis is in question, the cyst cavity may
be aspirated dry and the fluid sent for diagnostic studies including cytology, culture, and Gram stain.25 On gross inspection, solitary liver cysts appear bluish in color and contain clear, straw-colored fluid. Rarely, the fluid may be darker in color or even bilious, suggesting a connection with the biliary tree. When symptoms are present and can be attributed to the cyst, treatment of simple hepatic cysts is indicated. Ultrasonography-guided percutaneous aspiration alone has been attempted, but this simple procedure is associated with a recurrence rate of 100%.30 Although not providing permanent therapy, cyst aspiration has been advocated as a useful aid in diagnosis when the cause of the liver cyst is in doubt. Proponents of aspiration have also recommended this technique as a good therapeutic test to ascertain whether abdominal symptoms are related to the liver cyst. In cases when abdominal symptoms are not relieved by aspiration, other causes of abdominal pain should be sought and treatment of the liver cyst should be deferred.30 Attempts at improving percutaneous management of liver cysts have included instillation of a sclerosant after percutaneous aspiration of the cyst to achieve permanent ablation.31-33 The largest study of sclerosant therapy involved 30 congenital cysts with percuta-
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Figure 4. MRI appearance of a simple hepatic cyst in the left lobe of the liver. (A) T1-weighted image with low signal intensity. (B) T2-weighted image revealing very bright signal. (C) T1-weighted image after contrast infusion showing no contrast enhancement and sharp delineation of the simple cyst. c, simple hepatic cyst.
neous aspiration followed by instillation of 95% alcohol into the cyst cavity.31 Cysts recurred in 5 of 30 patients (17%), a significant improvement over aspiration alone. Reports of this technique involve small numbers of patients and insufficient followup to allow adequate evaluation of its efficacy. Most authors advocate surgical treatment for symptomatic hepatic cysts. When treated by open operation, a laparotomy with access to the upper abdomen should be performed. The liver should be examined and, when possible, the location and extent of the cyst evaluated grossly. All patients should also be evaluated by intraoperative ultrasonography. If the cyst is deep within the liver parenchyma or
not otherwise easily examined, its extent and anatomic relationship to biliary and vascular structures can be best evaluated with intraoperative ultrasonography. The cyst should be aspirated intraoperatively and the fluid examined. The contents should be sent for bacterial culture, Gram stain, and cytologic evaluation. A biopsy of the cyst wall is also warranted to rule out the presence of neoplastic cells.28 The biopsy should be taken from either suspicious areas with papillary projections or from the thickest part of the cyst wall. Careful pathologic examination of this biopsy specimen allows simple cysts to be distinguished from neoplastic cysts (Fig. 6). When the cyst protrudes from the liver, the ac-
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Figure 5. MRI of a biliary cystadenoma revealing the multilocular cystic nature of this lesion. (A) T1-weighted image. (B) T2weighted image. (C) Postcontrast image.
cessible cyst wall on the liver surface should be excised with electrocautery as described by Lin and associates.9 In most cases, because of close proximity of the cyst wall to nearby parenchymal and hilar structures, complete excision of the cyst wall cannot be performed.34,35 A portion of the cyst wall should be excised and the remaining cyst lining left behind with the cyst allowed to drain freely into the peritoneal cavity. Hemostasis on the cut edge of the cyst wall is obtained by electrocautery or by using a running suture along the length of the cyst-liver interface.36 Hepatic lobectomy for simple cysts has been reported and is associated with good results,37 but a procedure of this magnitude with its associated risk, is not often necessary. Resection may be necessary in patients with complex or recurrent cystic disease. The advantage of hepatic resection is its 0% recurrence rate. In rare cases where aspirated cyst fluid is bilious and it is suspected that a simple cyst communicates with the biliary tree, drainage can be achieved by Roux-en-Y cystjejunostomy. An at-
tempt to ligate the biliary communication within the cyst should also be made.28 Intraperitoneal drainage of a cyst known to communicate with the biliary system will result in formation of a postoperative biloma. Multiple series reporting surgical treatment of symptomatic simple hepatic cysts have been published.7,11,35,37-43 In most instances, these series reported one institution’s retrospective experience. Table 3 reviews several of these studies. Overall, wide surgical drainage, cyst excision, unroofing, and liver resection all provided excellent results (0% to 20% recurrence) with low morbidity and mortality (0% to 5%). In these series, experience with operative aspiration alone achieved poor results with high recurrence rates. Most aspirated patients ultimately required further surgical intervention.42 As with other surgical therapies, laparoscopy has been introduced in the treatment of hepatic cysts.7,42,44-52 Laparoscopy allows excellent exposure of the upper abdomen and has the potential to de-
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this should be considered the procedure of choice for treatment of these lesions.
Figure 6. Histologic sections of a simple cyst and a biliary cystadenoma. (A) Histopathologic evaluation of a simple cyst reveals a thin fibrous wall lined by cuboidal epithelium. (B) Histopathologic evaluation of a cystadenoma reveals a wall with papillary projections and thick folds of dense cellular stroma (S). The inner wall is lined by columnar epithelium (Inset—arrows).
crease postoperative pain while providing an effective minimally invasive therapy for liver cysts. Table 4 reviews the results of several reports of laparoscopic unroofing of liver cysts. Overall, success rate is high (⬎90%) with few complications and very low rates (10%) of symptomatic cyst recurrence. Although most studies have reported low symptomatic and radiographic recurrence rates, one study from Belgium47 revealed a radiographic cyst recurrence rate of 44%. In this study, only 25% of these radiographic recurrences were symptomatic. Because of the excellent overall results obtained with laparoscopic unroofing of simple liver cysts,
Neoplastic cysts Neoplastic cysts include biliary cystadenomas and biliary cystadenocarcinomas. Although not proved, it is believed that benign cystadenomas have the potential to undergo malignant transformation into biliary cystadenocarcinomas.53 Neoplastic liver cysts are even rarer than simple liver cysts and comprise only a small percentage of all cystic liver lesions.54 The epidemiology of neoplastic cysts resembles that of simple liver cysts. A majority of patients are female and in the fifth decade of life.54 In contrast to simple cysts, cystic tumors are often large and symptomatic. Most patients present with a history of abdominal discomfort or palpable abdominal mass. The diagnosis can often be made by ultrasonography or CT scan, which reveal that the cystic lesion in the liver is multiloculated with papillary projections within the cyst cavity. Imaging studies alone cannot differentiate between benign and malignant neoplastic cysts. Invasion of surrounding tissue noted either on preoperative studies or during operation suggests malignancy. Approximately 10% of neoplastic cysts are malignant.55 Definitive diagnosis requires intraoperative biopsy of the cyst wall. Treatment of neoplastic cysts is surgical. Because these cysts are commonly confused with simple liver cysts, patients are often treated with aspiration or unroofing before definitive surgical therapy.56 When the diagnosis of neoplastic cyst is made, complete resection is mandatory.57 Incomplete resection is uniformly associated with recurrence.58 Both formal hepatic resection and enucleation of biliary cystadenomas have been described. Formal hepatic resection has the advantage of complete removal of the lesion and allows for a controlled dissection of biliary and vascular structures. Resection is the only appropriate treatment for malignant biliary cystadenocarcinomas. Enucleation has been suggested as adequate treatment for neoplastic cysts with no signs of malignancy.56,59 It requires removal of the entire cyst with its surrounding wall and a small rim of liver parenchyma. This procedure has been recommended for large, centrally located cystadenomas where formal hepatic resection would be hazardous or require a total hep-
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Table 3. Results of Surgical Treatment of Liver Cysts Lead author
Year
n
Treatment
Longmire
1974
5
Edwards11
1987
6
Lai35
1990
7
Nelson39 HenneBruns40 Madariaga37 Herman41 Koperna42
1992 1993
3 6
1993 1996 1997
19 10 27
Martin7
1998
10
Kakizaki43
1998
9
Cyst excision (2) Cystenterostomy (2) Aspiration (1) Unroofing (3) Cyst excision (1) Lobectomy (2) Unroofing (4) Cyst excision (2) Fenestration (1) Unroofing Unroofing (3) Cyst excision (3) Resection Unroofing Fenestration (20) Resection (4) Cystjejunostomy (3) Unroofing (7) Resection (3) Unroofing (5) Cyst excision (2) Fenestration (2)
38
Complications
Recurrence
Followup (mo)
None
1*
Not reported
None
None
3–12
None
None
24⫹
None None
None None
18 5–32
Death (1/19) None Bleeding (1/27)
None None None
12–108 30 74
Not reported
2†
4–104
None
None
43
*Recurrence occurred in patient who underwent aspiration. † Both recurrences occurred in patients who underwent unroofing.
atectomy. Several small series reporting enucleation of biliary cystadenomas suggest that successful enucleation is associated with a low recurrence rate.54,57,59 Traumatic cysts Traumatic cysts are also rare and most information about this entity is derived from isolated case reports.60-65 In 1898, Whipple66 first reported a posttraumatic liver cyst, which occurred in a patient 1 week after suffering blunt abdominal trauma with parenchymal liver injury. Many liver injuries do not acutely require surgical exploration because bleeding often ceases spontaneously and hepatic injuries are now commonly approached nonoperatively.65 When an injured biliary structure continues to leak into a hematoma cavity, a cyst containing bile and blood may form.34 If biliary leakage continues, the cyst grows until its size causes compressive symptoms. Patients with posttraumatic cysts present in a delayed fashion with abdominal pain or abdominal fullness.67 Posttraumatic liver cysts can present as soon as days after abdominal trauma to as late as months or years after injury.62,65,67,68 The diagnosis of posttraumatic cyst is made with ultrasonography or abdominal CT scan as previously described.
These patients are generally young, reflecting the age profile of blunt abdominal trauma. When traumatic cysts are symptomatic, they should be treated surgically. Most authors describe simple excision of the cyst wall with or without omental transposition into the cyst cavity and external drainage.64,65 With the increasing use of nonoperative therapy for liver injury, this type of cyst will likely increase in frequency. In summary, the various cystic lesions of the liver can usually be distinguished by imaging studies. Simple liver cysts are commonly noted incidentally. Treatment of these cysts is based on whether or not they are symptomatic. When symptomatic, simple cysts can be treated with unroofing, total excision, or liver resection with good long-term results. With advances in minimally invasive techniques, cyst unroofing has been performed laparoscopically with equally good results. Neoplastic cysts require complete resection to prevent recurrence. Traumatic cysts occur secondary to liver injury. They occur in a younger population and present in a delayed fashion. When symptomatic, posttraumatic cysts may be excised with good success.
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Table 4. Results of Laparoscopic Treatment of Liver Cysts Author
Year
n
Morino
1994
4
Ooi45
1994
3
Krahenbuhl46
1996
8
Gigot47
1996
17
Koperna42
1997
5
Hansen48
1997
17
Fabian49
1997
10
Martin7
1998
13
Diez50
1998
10
Katkhouda51
1999
16
Zacheri52
2000
11
44
Treatment Laparoscopic fenestration Laparoscopic marsupialization Laparoscopic fenestration Laparoscopic fenestration Laparoscopic fenestration Laparoscopic cyst wall excision Laparoscopic fenestration Laparoscopic unroofing Laparoscopic unroofing Laparoscopic fenestration Laparoscopic fenestration
Length of Stay (d)
Complications
Recurrence
4
None
None
8–22
Not reported
None
None
3–12.5
8.5
None
1/8
4.6
None
8/17*
10
Not reported
1/5
1/5
74
2.5
3/17
1/17
30
5
None
None
25.5
3
3/13
1/13
25
4
None
None
6–36
4.7
1/16
None
30
5
None
1/7†
36
Followup (mo)
12.6
*Only two of these eight recurrences were symptomatic. † Not all patients were available for followup.
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27. Walt AJ. Cysts and benign tumors of the liver. Surg Clin North Am 1977;57:449–464. 28. Doty JE, Tompkins RK. Management of cystic disease of the liver. Surg Clin North Am 1989;69:285–295. 29. Rashed A, May RE, Williamson RCN. The management of large congenital liver cysts. Postgrad Med J 1982;58:536–541. 30. Saini S, Mueller PR, Ferrucci JT, et al. Percutaneous aspiration of hepatic cysts does not provide definitive therapy. Am J Roentgenol 1983;141:559–560. 31. Simonetti G, Profili S, Sergiacomi GL, et al. Percutaneous treatment of hepatic cysts by aspiration and sclerotherapy. Cardiovasc Intervent Radiol 1993;16:81–84. 32. McCullough KM. Alcohol sclerotherapy of simple parenchymal liver cysts. Australas Radiol 1993;37:177–181. 33. vanSonnenberg E, Wroblicka JT, D’Agostino HB, et al. Symptomatic hepatic cysts: percutaneous drainage and sclerosis. Radiology 1994;190:387–392. 34. Jones RS. Surgical management of non-parasitic liver cysts. In: Blumgart LH, ed. Surgery of the liver and biliary tract. 2nd ed. Edinburgh: Churchill Livingstone; 1988:1211–1218. 35. Lai ECS, Wong J. Symptomatic nonparasitic cysts of the liver. World J Surg 1990;14:452–456. 36. Langer B, Gallinger S. Cystic disease of the liver. In: Zuidema GD, Orringer MB, Ritchie WP Jr, Turcotte JG, Condon RE, Nyhus LM, eds. Shackelford’s surgery of the alimentary tract. 3rd ed. Philadelphia: WB Saunders; 1991:428–442. 37. Madariaga JR, Iwatsuki S, Starzl TE, et al. Hepatic resection for cystic lesions of the liver. Ann Surg 1993;218:610–614. 38. Longmire WP, Trout HH, Greenfield J, et al. Elective hepatic surgery. Ann Surg 1974;179:712–721. 39. Nelson J, Davidson D, McKittrick JE. Simple surgical treatment of nonparasitic hepatic cysts. Am Surg 1992;58:755–757. 40. Henne-Bruns D, Klomp HJ, Kremmer B. Non-parasitic liver cysts and polycystic liver disease: results of surgical treatment. Hepatogastroenterol 1993;40:1–5. 41. Herman P, Klajner S, Borges PCM. Tratamento cirurgico do cisto solitario de figado. Arq Gastroenterol 1996;33:6–9. 42. Koperna T, Vogl S, Satzinger U, Schulz F. Nonparasitic cysts of the liver: results and options of surgical management. World J Surg 1997;21:850–855. 43. Kakizaki K, Yamauchi H, Teshima S. Symptomatic liver cyst: special reference to surgical management. J Hepato-Biliary-Pancreatic Surg 1998;5:192–195. 44. Morino M, De Giuli M, Festa V, Garrone C. Laparoscopic management of symptomatic nonparasitic cysts of the liver— indications and results. Ann Surg 1994;219:157–164. 45. Ooi LLPJ, Cheong LH, Mack POP. Laparoscopic marsupialization of liver cysts. Aust N Z J Surg 1994;64:262–263. 46. Krahenbuhl L, Baer HU, Renzulli P, et al. Laparoscopic management of nonparasitic symptom-producing solitary hepatic cysts. J Am Coll Surg 1996;183:493–498. 47. Gigot JF, Legrand M, Hubens G, et al. Laparoscopic treatment of nonparasitic liver cysts: adequate selection of patients and surgical technique. World J Surg 1996;20:556–561.
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48. Hansen P, Bhoyrul S, Legha P, et al. Laparoscopic treatment of liver cysts. J Gastrointest Surg 1997;1:53–60. 49. Fabiani P, Mazza D, Toouli J, et al. Laparoscopic fenestration of symptomatic non-parasitic cysts of the liver. Br J Surg 1997;84:321–322. 50. Diez J, Decoud J, Gutierrez L, et al. Laparoscopic treatment of symptomatic cysts of the liver. Br J Surg 1998;85:25–27. 51. Katkhouda N, Hurwitz M, Gugenheim J. Laparoscopic management of benign solid and cystic lesions of the liver. Ann Surg 1999;229:460–466. 52. Zacheri J, Scheuba C, Imhof M, et al. Long-term results after laparoscopic unroofing of solitary symptomatic congenital liver cysts. Surg Endosc 2000;14:50–62. 53. Woods G. Biliary cystadenocarcinoma: case report of hepatic malignancy originating in benign cystadenoma. Cancer 1981; 47:2936–2940. 54. Marcial MA, Hauser SC, Cibas ES, Braver J. Intrahepatic biliary cystadenoma—clinical, radiological and pathological findings. Dig Dis Sci 1986;31:884–888. 55. Ishak KG, Willis GW, Cummins SD, Bullock AA. Biliary cystadenoma and cystadenocarcinoma: report of 14 cases and review of the literature. Cancer 1977;38:322–338. 56. Jenkins RL, Johnson LB, Lewis WD. Surgical approach to benign liver tumors. Semin Liver Dis 1994;14:178–189. 57. Lau WY, Chow CH, Leung ML. Total excision of mucinous biliary cystadenoma. Aust N Z J Surg 1990;60:226–228. 58. Lewis WD, Jenkins RL, Rossi RL, et al. Surgical management of biliary cystadenoma. A report of 15 cases. Arch Surg 1988;123: 563–568. 59. Pinson CW, Munson JL, Rossi RL, Braasch JW. Enucleation of intrahepatic biliary cystadenomas. Surg Gynecol Obstet 1989; 168:535–537. 60. Robertson DE, Graham RR. Rupture of the liver without tear of the capsule. Ann Surg 1933;98:899–903. 61. Poth EJ, DeLoach AW. Pseudocyst of the liver: report of a case. Arch Surg 1949;59:925–927. 62. Kerkes ES, Ewing J. Traumatic liver cyst. Radiology 1950;55: 861–864. 63. Hallenbeck GA, Fricke RW. Traumatic bile cyst of the liver: report of two cases. Proc Mayo Clin 1950;25:648–651. 64. Thomas CS, Adkins RB, Lanier VC, Foster JH. The surgical management of intrahepatic hematomas. Am Surg 1970;36: 171–176. 65. Chuang JH, Huang SC. Posttraumatic hepatic cyst—an unusual sequela of liver injury in the era of imaging. J Pediatr Surg 1996;31:272–274. 66. Whipple C. A case of traumatic rupture of the liver; formation of cystic swelling containing bile-stained fluid; incision and drainage; recovery. Lancet 1898;1:719. 67. Henson SW, Hallenbeck GA, Gray HK, Dockerty MB. Benign tumors of the liver. V. Traumatic cysts. Surg Gynecol Obstet 1957;104:302–306. 68. Heslop JH. Complications of liver resection for trauma. Aust N Z J Surg 1974;44:329–335.
Solitary Hepatic Cysts Robert A Cowles, MD, Michael W Mulholland, MD, PhD, FACS
techniques have generated new information on the incidence of liver cysts. In 1989, a European study reported the incidence of simple hepatic cysts in 1,695 patients who had been referred for abdominal or pelvic ultrasonography. In this population, the overall incidence of liver cysts was 2.5%, with a sharp increase in incidence noted in individuals more than 60 years of age.4 A separate European study reported the incidence of liver cysts in more than 26,000 patients undergoing upper abdominal ultrasonography. A total of 1,235 liver cysts were identified for a calculated incidence of 4.75%. In this study, 61.2% of cysts were classified as simple hepatic cysts resulting in an incidence of simple cysts of 2.8%.5 More than 92% of cysts identified in this latter study were in patients more than 40 years of age.5 Hepatic cysts are encountered more often in female patients. The female to male ratio is estimated to be 1.5:16 and cysts are symptomatic more often in women than in men.7 The pathogenesis of hepatic cysts is unclear, but likely related to the type of cyst. Solitary benign nonparasitic cysts are believed to be congenital. Solitary benign cysts are lined by cuboidal epithelium and are thought to arise from abnormal development of intrahepatic bile ducts in utero. These collections of aberrant ducts enlarge slowly and only result in symptoms later in life. In contrast, neoplastic and traumatic cysts are acquired. Cystic neoplasms of the liver include benign biliary cystadenomas and the malignant variant, the biliary cystadenocarcinoma. The cause of cystic neoplasms is unknown. Traumatic cysts are acquired and occur from continued bile leakage from an injured intrahepatic bile duct after abdominal trauma.
The treatment of liver cysts continues to evolve in terms of diagnosis and surgical therapy. In the past, hepatic cysts were usually discovered at laparotomy, but they have become an increasingly common incidental finding on radiographic studies such as ultrasonography and CT scan. Occasionally liver cysts present as symptomatic abdominal masses. Hepatic cysts can be divided into two general categories: congenital and acquired (Table 1). Because the cause and treatment of cystic lesions of the liver differ, depending on the lesion and on the presence or absence of symptoms, it is important to be familiar with the appropriate evaluation and management of these masses. This article reviews common presentations, diagnostic methods, and treatment of congenital and acquired liver cysts. Discussion of infectious cysts, including amoebic, pyogenic, and hydatid cysts, and complex multicystic liver disease, has been excluded from this review. INCIDENCE AND PATHOGENESIS Hepatic cysts are noted frequently as incidental findings at laparotomy, but determining the precise incidence of hepatic cysts is difficult. Early estimates of the incidence of liver cysts were generated from autopsy studies. In a report of 20,000 autopsies, 28 hepatic cysts were found, for a calculated incidence of 0.14%.1 Other early series reported similarly low incidences of 0.17% and 0.53%.2,3 More recently, improvements in radiographic technology and increased use of abdominal imaging Received April 20, 2000; Accepted May 24, 2000. From the Section of General Surgery, Department of Surgery, University of Michigan, Ann Arbor, MI. Correspondence address: Michael W Mulholland, MD, PhD, FACS, Department of Surgery, 2920B Taubman Center, Box 0331, 1500 East Medical Center Dr, Ann Arbor, MI 48109-0331. © 2000 by the American College of Surgeons Published by Elsevier Science Inc.
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Table 1. Categories of Cystic Liver Disease Congenital
Acquired
Solitary benign nonparasitic cysts Polycystic liver disease Caroli’s disease
Neoplastic cysts Traumatic cysts Infectious cysts
PRESENTATION The presentation of patients with hepatic cysts is variable and dependent on the type of cyst. Most cysts are asymptomatic, with the liver lesion noted during ultrasonography or on CT scan performed for an unrelated reason. Several studies suggest that patients with nonparasitic and neoplastic cysts most commonly present after age 50 and are more likely female. Trauma is common in younger individuals, so the population of patients with traumatic cysts is younger than the population with simple congenital cysts. Symptoms and physical examination Only a small fraction of nonparasitic cysts are symptomatic. An extended experience at the Mayo Clinic between 1907 and 1971 revealed that only 24% of simple cysts (27 of 120) were symptomatic.2,8 Symptoms were more commonly present in patients with neoplastic and traumatic cysts, although these cysts were encountered with much lower frequency. Although hepatic cysts usually become symptomatic in the fourth or fifth decades of life, cases involving children and young adults have been reported.9-12 Symptoms attributed to liver cysts are listed in Table 2. Abdominal pain and abdominal mass are the most frequently noted complaints and are present in more than 50% of patients. Other less common complaints include nausea, vomiting, early satiety, fatigue, and jaundice.11,13-15 Symptoms usually result from mass effect caused by the enlarging cyst. Some patients complain of dull, aching pain and others have seTable 2. Common Symptoms Attributed to Liver Cysts Symptom
Frequency (%)
Abdominal pain: chronic, dull or acute, severe Abdominal mass Jaundice Early satiety, nausea, vomiting
50–93 25–53 7–13 20–42
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vere sharp, episodic pain requiring narcotic analgesics for relief. Making an immediate distinction between simple, neoplastic, and traumatic cysts is difficult although an antecedent history of abdominal trauma or an earlier history of simple cyst can be a clue to the diagnosis. Physical examination may reveal a palpable abdominal mass or hepatomegaly, but these findings are nonspecific and are not sufficient to secure a definitive diagnosis. DIAGNOSTIC EVALUATION Imaging studies Because most hepatic cysts are either asymptomatic or produce only mild, nonspecific symptoms, and because they are difficult to evaluate by physical examination, imaging studies are of paramount importance to the physician caring for affected patients. In many instances, imaging studies are the means by which these lesions are initially discovered. The improvement in abdominal imaging techniques during the past two decades has greatly facilitated the diagnosis of abdominal pathology including hepatic cysts. Ultrasonography, CT scan, and less frequently, MRI studies are used to classify and anatomically delineate cystic hepatic lesions. Although simple hepatic cysts and traumatic cysts are distinct clinical entities, their appearance on imaging studies is often similar and the radiographic descriptions within this review pertain to both types of cysts. The distinction between simple or traumatic cysts and neoplastic cysts is most important and will be stressed. Ultrasonography is an inexpensive, simple, and noninvasive technique for evaluation of liver cysts. Ultrasonography is considered to be the most accurate imaging modality for the diagnosis of hepatic cysts with sensitivity and specificity of greater than 90%.16,17 Ultrasonography is recommended as an initial diagnostic modality, because when compared with CT scan and MRI, it is easy to perform, portable, and provides considerable diagnostic information about lesions in the liver.18-20 On ultrasonographic examination, liver cysts appear as anechoic masses with smooth margins and a thin, imperceptible wall (Fig. 1).17,19,21 Back wall enhancement is generally seen because of differential reflection of sound waves by the cyst fluid and the posterior wall
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Figure 1. (A) Abdominal ultrasound performed for evaluation of right upper quadrant pain. The study reveals a small anechoic round lesion with a thin wall diagnostic for liver cyst (arrow). (B) Abdominal ultrasound in this patient revealed a larger simple hepatic cyst within the substance of the liver. (C) Ultrasound appearance of a large simple hepatic cyst. The interface between the cyst and the liver parenchyma is seen (arrowheads). This cyst was symptomatic and measured 15 cm in greatest dimension.
of the cyst with its surrounding liver parenchyma (Fig. 1).19 Ultrasonography allows distinction between cystic and solid lesions within the liver. When ultrasonography reveals a cystic structure, it can also help to differentiate types of cysts. Although all hepatic cysts are anechoic on ultrasound, biliary cystadenomas can be differentiated from
simple or traumatic cysts based on the internal ultrasonographic anatomy. In contrast to simple cysts, which are unilocular, biliary cystadenomas have a septated, multilocular appearance on ultrasound. The presence of septae should suggest the diagnosis of neoplastic cyst.21 The presence of debris within the cyst cavity by ultrasonography is
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Figure 2. (A) Contrast-enhanced abdominal CT scan performed for staging of a pancreatic carcinoma. This imaging study incidentally revealed a small, asymptomatic simple hepatic cyst in the left lobe of the liver (arrow). Note the water density of the cyst cavity and the thin, imperceptible wall. (B) Contrast-enhanced abdominal CT scan revealing a large centrally located simple liver cyst.
suggestive of malignancy and should prompt the clinician to pursue further investigation.22 Ultrasonography is also able to provide additional information when jaundice is present. In this scenario, ultrasonography can be used to evaluate the biliary tree for intra- and extrahepatic biliary dilatation secondary to mass effect caused by a large liver cyst. Abdominal CT scan is used to delineate lesions
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in the liver. Although ultrasound examination can define whether a liver lesion is solid or cystic and can suggest a diagnosis of hepatic cyst, CT scan is superior in determining the location and spatial relationships between liver cysts and surrounding structures such as blood vessels, bile ducts, and hollow viscera. For these spatial relations to be appreciated, abdominal CT scans should be performed with oral and intravenous contrast. The infusion of intravenous contrast should be carefully timed and should occur with a short delay before initiation of scanning.23 This protocol will allow the liver to be scanned during the time of maximal hepatic contrast enhancement.23 On CT scan, hepatic cysts are nonenhancing, fluid (ie, water) density lesions with a thin, uniform wall (Fig. 2). When liver cysts are small (⬍1cm) the CT and ultrasound-based diagnosis of benign cyst can be more difficult and generally requires repeat imaging studies for followup if clinically indicated.23 When water density cystic structures seen on abdominal CT scan are septated and multilocular or when papillary projections are present within the cyst, the diagnoses of cystadenoma or cystadenocarcinoma should be considered (Fig. 3). MRI scanning is rarely the initial imaging modality for diagnosis of hepatic cysts. Knowledge of MRI characteristics is useful when cystic structures are identified on MRI done for another reason. When seen on MRI, simple hepatic cysts are wellcircumscribed lesions that are very hypointense on T1-weighted images and hyperintense on T2weighted images24 (Fig. 4). If there has been hemorrhage into a hepatic cyst, this appearance changes and the cyst becomes hyperintense on both T1- and T2-weighted images. Descriptions of the MRI appearance of biliary cystadenomas and cystadenocarcinomas are limited, but the multilocular nature of this lesion is evident on MRI (Fig. 5). Unfortunately, even MRI imaging techniques cannot accurately distinguish whether these neoplasms are benign or malignant. Additional imaging modalities are occasionally useful. Plain x-rays or upper gastrointestinal contrast studies may reveal elevation of the right hemidiaphragm or compression of normal intraabdominal structures.25 Liver scintiscans are consistent with a “cold” cyst. Angiography will reveal the cyst as an
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avascular mass with stretching or displacement of surrounding vessels and perhaps causing mass effect.26 These studies are rarely necessary and are not generally helpful if ultrasonography, CT scan, or both have previously been performed. Laboratory evaluation in patients with liver cysts should be tailored to the underlying condition, age, and findings on physical examination. Routine laboratory values including liver function tests are normal and most studies have reported no significant abnormality in any laboratory parameter.11,27 On rare occasions, elevations in bilirubin will be noted, from biliary obstruction caused by a large cyst. Ecchinococcal serology should be obtained in all patients with cystic lesions of the liver. TREATMENT The treatment of cystic liver masses depends on factors ascertained preoperatively: the presence or absence of symptoms and the appearance of the cyst on ultrasound or CT scan.
Figure 3. Abdominal CT scan performed for right upper quadrant abdominal pain. A biliary cystadenoma is seen with characteristic internal septations. This lesion was confirmed to be a cystadenoma at laparotomy.
Simple cysts Successful treatment of simple hepatic cysts begins with a focused history and physical examination. The physician should specifically seek to elicit a history of abdominal pain or increasing abdominal girth. The abdomen should be carefully examined for the presence of masses or hepatomegaly. Often, the operative or radiographic discovery of these liver lesions occurs incidentally and questions regarding abdominal symptomatology are asked in retrospect. When simple hepatic cysts are found incidentally by abdominal imaging and are determined to be asymptomatic, conservative management is appropriate.28,29 Likewise, simple hepatic cysts encountered incidentally at laparotomy should be treated conservatively. This expectant approach is based on the observation that a large majority (80% to 95%) of liver cysts remain asymptomatic.2,6 In addition, when symptoms related to a cyst do occur, treatment can be instituted with low morbidity and virtually no mortality. On occasion, an intraoperatively encountered cyst is pedunculated, and easily excised. These pedunculated cysts are thought to be at risk for torsion, and if possible, a simple cyst resection has been recommended.25,28 When a cyst is encountered during an abdominal exploration and the diagnosis is in question, the cyst cavity may
be aspirated dry and the fluid sent for diagnostic studies including cytology, culture, and Gram stain.25 On gross inspection, solitary liver cysts appear bluish in color and contain clear, straw-colored fluid. Rarely, the fluid may be darker in color or even bilious, suggesting a connection with the biliary tree. When symptoms are present and can be attributed to the cyst, treatment of simple hepatic cysts is indicated. Ultrasonography-guided percutaneous aspiration alone has been attempted, but this simple procedure is associated with a recurrence rate of 100%.30 Although not providing permanent therapy, cyst aspiration has been advocated as a useful aid in diagnosis when the cause of the liver cyst is in doubt. Proponents of aspiration have also recommended this technique as a good therapeutic test to ascertain whether abdominal symptoms are related to the liver cyst. In cases when abdominal symptoms are not relieved by aspiration, other causes of abdominal pain should be sought and treatment of the liver cyst should be deferred.30 Attempts at improving percutaneous management of liver cysts have included instillation of a sclerosant after percutaneous aspiration of the cyst to achieve permanent ablation.31-33 The largest study of sclerosant therapy involved 30 congenital cysts with percuta-
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Figure 4. MRI appearance of a simple hepatic cyst in the left lobe of the liver. (A) T1-weighted image with low signal intensity. (B) T2-weighted image revealing very bright signal. (C) T1-weighted image after contrast infusion showing no contrast enhancement and sharp delineation of the simple cyst. c, simple hepatic cyst.
neous aspiration followed by instillation of 95% alcohol into the cyst cavity.31 Cysts recurred in 5 of 30 patients (17%), a significant improvement over aspiration alone. Reports of this technique involve small numbers of patients and insufficient followup to allow adequate evaluation of its efficacy. Most authors advocate surgical treatment for symptomatic hepatic cysts. When treated by open operation, a laparotomy with access to the upper abdomen should be performed. The liver should be examined and, when possible, the location and extent of the cyst evaluated grossly. All patients should also be evaluated by intraoperative ultrasonography. If the cyst is deep within the liver parenchyma or
not otherwise easily examined, its extent and anatomic relationship to biliary and vascular structures can be best evaluated with intraoperative ultrasonography. The cyst should be aspirated intraoperatively and the fluid examined. The contents should be sent for bacterial culture, Gram stain, and cytologic evaluation. A biopsy of the cyst wall is also warranted to rule out the presence of neoplastic cells.28 The biopsy should be taken from either suspicious areas with papillary projections or from the thickest part of the cyst wall. Careful pathologic examination of this biopsy specimen allows simple cysts to be distinguished from neoplastic cysts (Fig. 6). When the cyst protrudes from the liver, the ac-
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Figure 5. MRI of a biliary cystadenoma revealing the multilocular cystic nature of this lesion. (A) T1-weighted image. (B) T2weighted image. (C) Postcontrast image.
cessible cyst wall on the liver surface should be excised with electrocautery as described by Lin and associates.9 In most cases, because of close proximity of the cyst wall to nearby parenchymal and hilar structures, complete excision of the cyst wall cannot be performed.34,35 A portion of the cyst wall should be excised and the remaining cyst lining left behind with the cyst allowed to drain freely into the peritoneal cavity. Hemostasis on the cut edge of the cyst wall is obtained by electrocautery or by using a running suture along the length of the cyst-liver interface.36 Hepatic lobectomy for simple cysts has been reported and is associated with good results,37 but a procedure of this magnitude with its associated risk, is not often necessary. Resection may be necessary in patients with complex or recurrent cystic disease. The advantage of hepatic resection is its 0% recurrence rate. In rare cases where aspirated cyst fluid is bilious and it is suspected that a simple cyst communicates with the biliary tree, drainage can be achieved by Roux-en-Y cystjejunostomy. An at-
tempt to ligate the biliary communication within the cyst should also be made.28 Intraperitoneal drainage of a cyst known to communicate with the biliary system will result in formation of a postoperative biloma. Multiple series reporting surgical treatment of symptomatic simple hepatic cysts have been published.7,11,35,37-43 In most instances, these series reported one institution’s retrospective experience. Table 3 reviews several of these studies. Overall, wide surgical drainage, cyst excision, unroofing, and liver resection all provided excellent results (0% to 20% recurrence) with low morbidity and mortality (0% to 5%). In these series, experience with operative aspiration alone achieved poor results with high recurrence rates. Most aspirated patients ultimately required further surgical intervention.42 As with other surgical therapies, laparoscopy has been introduced in the treatment of hepatic cysts.7,42,44-52 Laparoscopy allows excellent exposure of the upper abdomen and has the potential to de-
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this should be considered the procedure of choice for treatment of these lesions.
Figure 6. Histologic sections of a simple cyst and a biliary cystadenoma. (A) Histopathologic evaluation of a simple cyst reveals a thin fibrous wall lined by cuboidal epithelium. (B) Histopathologic evaluation of a cystadenoma reveals a wall with papillary projections and thick folds of dense cellular stroma (S). The inner wall is lined by columnar epithelium (Inset—arrows).
crease postoperative pain while providing an effective minimally invasive therapy for liver cysts. Table 4 reviews the results of several reports of laparoscopic unroofing of liver cysts. Overall, success rate is high (⬎90%) with few complications and very low rates (10%) of symptomatic cyst recurrence. Although most studies have reported low symptomatic and radiographic recurrence rates, one study from Belgium47 revealed a radiographic cyst recurrence rate of 44%. In this study, only 25% of these radiographic recurrences were symptomatic. Because of the excellent overall results obtained with laparoscopic unroofing of simple liver cysts,
Neoplastic cysts Neoplastic cysts include biliary cystadenomas and biliary cystadenocarcinomas. Although not proved, it is believed that benign cystadenomas have the potential to undergo malignant transformation into biliary cystadenocarcinomas.53 Neoplastic liver cysts are even rarer than simple liver cysts and comprise only a small percentage of all cystic liver lesions.54 The epidemiology of neoplastic cysts resembles that of simple liver cysts. A majority of patients are female and in the fifth decade of life.54 In contrast to simple cysts, cystic tumors are often large and symptomatic. Most patients present with a history of abdominal discomfort or palpable abdominal mass. The diagnosis can often be made by ultrasonography or CT scan, which reveal that the cystic lesion in the liver is multiloculated with papillary projections within the cyst cavity. Imaging studies alone cannot differentiate between benign and malignant neoplastic cysts. Invasion of surrounding tissue noted either on preoperative studies or during operation suggests malignancy. Approximately 10% of neoplastic cysts are malignant.55 Definitive diagnosis requires intraoperative biopsy of the cyst wall. Treatment of neoplastic cysts is surgical. Because these cysts are commonly confused with simple liver cysts, patients are often treated with aspiration or unroofing before definitive surgical therapy.56 When the diagnosis of neoplastic cyst is made, complete resection is mandatory.57 Incomplete resection is uniformly associated with recurrence.58 Both formal hepatic resection and enucleation of biliary cystadenomas have been described. Formal hepatic resection has the advantage of complete removal of the lesion and allows for a controlled dissection of biliary and vascular structures. Resection is the only appropriate treatment for malignant biliary cystadenocarcinomas. Enucleation has been suggested as adequate treatment for neoplastic cysts with no signs of malignancy.56,59 It requires removal of the entire cyst with its surrounding wall and a small rim of liver parenchyma. This procedure has been recommended for large, centrally located cystadenomas where formal hepatic resection would be hazardous or require a total hep-
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Table 3. Results of Surgical Treatment of Liver Cysts Lead author
Year
n
Treatment
Longmire
1974
5
Edwards11
1987
6
Lai35
1990
7
Nelson39 HenneBruns40 Madariaga37 Herman41 Koperna42
1992 1993
3 6
1993 1996 1997
19 10 27
Martin7
1998
10
Kakizaki43
1998
9
Cyst excision (2) Cystenterostomy (2) Aspiration (1) Unroofing (3) Cyst excision (1) Lobectomy (2) Unroofing (4) Cyst excision (2) Fenestration (1) Unroofing Unroofing (3) Cyst excision (3) Resection Unroofing Fenestration (20) Resection (4) Cystjejunostomy (3) Unroofing (7) Resection (3) Unroofing (5) Cyst excision (2) Fenestration (2)
38
Complications
Recurrence
Followup (mo)
None
1*
Not reported
None
None
3–12
None
None
24⫹
None None
None None
18 5–32
Death (1/19) None Bleeding (1/27)
None None None
12–108 30 74
Not reported
2†
4–104
None
None
43
*Recurrence occurred in patient who underwent aspiration. † Both recurrences occurred in patients who underwent unroofing.
atectomy. Several small series reporting enucleation of biliary cystadenomas suggest that successful enucleation is associated with a low recurrence rate.54,57,59 Traumatic cysts Traumatic cysts are also rare and most information about this entity is derived from isolated case reports.60-65 In 1898, Whipple66 first reported a posttraumatic liver cyst, which occurred in a patient 1 week after suffering blunt abdominal trauma with parenchymal liver injury. Many liver injuries do not acutely require surgical exploration because bleeding often ceases spontaneously and hepatic injuries are now commonly approached nonoperatively.65 When an injured biliary structure continues to leak into a hematoma cavity, a cyst containing bile and blood may form.34 If biliary leakage continues, the cyst grows until its size causes compressive symptoms. Patients with posttraumatic cysts present in a delayed fashion with abdominal pain or abdominal fullness.67 Posttraumatic liver cysts can present as soon as days after abdominal trauma to as late as months or years after injury.62,65,67,68 The diagnosis of posttraumatic cyst is made with ultrasonography or abdominal CT scan as previously described.
These patients are generally young, reflecting the age profile of blunt abdominal trauma. When traumatic cysts are symptomatic, they should be treated surgically. Most authors describe simple excision of the cyst wall with or without omental transposition into the cyst cavity and external drainage.64,65 With the increasing use of nonoperative therapy for liver injury, this type of cyst will likely increase in frequency. In summary, the various cystic lesions of the liver can usually be distinguished by imaging studies. Simple liver cysts are commonly noted incidentally. Treatment of these cysts is based on whether or not they are symptomatic. When symptomatic, simple cysts can be treated with unroofing, total excision, or liver resection with good long-term results. With advances in minimally invasive techniques, cyst unroofing has been performed laparoscopically with equally good results. Neoplastic cysts require complete resection to prevent recurrence. Traumatic cysts occur secondary to liver injury. They occur in a younger population and present in a delayed fashion. When symptomatic, posttraumatic cysts may be excised with good success.
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Table 4. Results of Laparoscopic Treatment of Liver Cysts Author
Year
n
Morino
1994
4
Ooi45
1994
3
Krahenbuhl46
1996
8
Gigot47
1996
17
Koperna42
1997
5
Hansen48
1997
17
Fabian49
1997
10
Martin7
1998
13
Diez50
1998
10
Katkhouda51
1999
16
Zacheri52
2000
11
44
Treatment Laparoscopic fenestration Laparoscopic marsupialization Laparoscopic fenestration Laparoscopic fenestration Laparoscopic fenestration Laparoscopic cyst wall excision Laparoscopic fenestration Laparoscopic unroofing Laparoscopic unroofing Laparoscopic fenestration Laparoscopic fenestration
Length of Stay (d)
Complications
Recurrence
4
None
None
8–22
Not reported
None
None
3–12.5
8.5
None
1/8
4.6
None
8/17*
10
Not reported
1/5
1/5
74
2.5
3/17
1/17
30
5
None
None
25.5
3
3/13
1/13
25
4
None
None
6–36
4.7
1/16
None
30
5
None
1/7†
36
Followup (mo)
12.6
*Only two of these eight recurrences were symptomatic. † Not all patients were available for followup.
References 1. Eliason EL, Smith DC. Solitary nonparasitic cyst of the liver: case report. Clinics 1944;3:607. 2. Sanfelippo PM, Beahrs OH, Weiland LH. Cystic disease of the liver. Ann Surg 1974;179:922–925. 3. Feldman M. Polycystic disease of the liver. Am J Gastroenterol 1958;28:83–86. 4. Gaines PA, Sampson MA. The prevalence and characterization of simple hepatic cysts by ultrasound examination. Br J Radiol 1989;62:335–337. 5. Caremani M, Vincenti A, Benci A, et al. Ecographic epidemiology of non-parasitic hepatic cysts. J Clin Ultrasound 1993;21: 115–118. 6. Benhamou JP, Menu Y. Non-parasitic cystic diseases of the liver and intrahepatic biliary tree. In: Blumgart LH, ed. Surgery of the liver and biliary tract. 2nd ed. Edinburgh: Churchill Livingstone; 1994:1197–1210. 7. Martin IJ, McKinley AJ, Currie EJ, et al. Tailoring the management of nonparasitic liver cysts. Ann Surg 1998;228:167–172. 8. Henson SW, Gray HK, Dockerty MB. Benign tumors of the liver. III. Solitary cysts. Surg Gynecol Obstet 1956;103:607– 612. 9. Lin TY, Chen CC, Wang SM. Treatment of non-parasitic cystic disease of the liver: a new approach to therapy with polycystic liver. Ann Surg 1968;168:921–927. 10. Sood SC, Watson A. Solitary cyst of the liver presenting as an abdominal emergency. Postgrad Med J 1974;50:48–50. 11. Edwards JD, Eckhauser FE, Knol JA, et al. Optimizing surgical management of symptomatic solitary hepatic cysts. Am Surg 1987;53:510–514. 12. Ramesh J, Walrond ER, Prussia PR, et al. Congenital solitary non-parasitic cyst of the liver. W I Med J 1995;44:36–37.
13. Trinkl W, Sassaris M, Hunter FM. Nonsurgical treatment for symptomatic nonparasitic liver cyst. Am J Gastroenterol 1985; 80:907–911. 14. Hudson EK. Obstructive jaundice from solitary hepatic cyst. Am J Gastroenterol 1963;39:161–164. 15. Kanai T, Kenmochi T, Takabayashi T, et al. Obstructive jaundice caused by a huge cyst riding on the hilum: report of a case. Surg Today 1999;29:791–794. 16. Spiegel RM, King DL, Green WM. Ultrasonography of primary cysts of the liver. Am J Roentgenol 1978;131:235–238. 17. Taylor KJW, Richman TS. Diseases of the liver. Semin Roentgenol 1983;18:94–101. 18. Sceible W. A diagnostic algorithm for liver masses. Semin Roentgenol 1983;18:84–86. 19. Marn CS, Bree RL, Silver TM. Ultrasonography of liver— technique and focal and diffuse disease. Radiol Clin North Am 1991;29:1151–1170. 20. Schwartz JH, Ellison EC. Focal liver lesions—evaluation of simple and complex cysts. Postgrad Med 1994;95:149–152. 21. Mergo PJ, Ros PR. Benign lesions of the liver. Radiol Clin North Am 1998;36:319–331. 22. Iemoto Y, Kondo Y, Nakano T, et al. Biliary cystadenocarcinoma diagnosed by liver biopsy performed under ultrasonographic guidance. Gastroenterol 1983;84:399–403. 23. Foley WD, Jochem RJ. Computed tomography—focal and diffuse liver disease. Radiol Clin North Am 1991;29:1213–1233. 24. Kanzer GK, Weinreb JC. Magnetic resonance imaging of diseases of the liver and biliary system. Radiol Clin North Am 1991;29:1259–1284. 25. Haddad AR, Westbrook KC, Graham GG, et al. Symptomatic nonparasitic liver cysts. Am J Surg 1977;134:739–744. 26. Freeny PC. Angiography of hepatic neoplasms. Semin Roentgenol 1983;18:114–122.
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