(Radiographics. 2002;22:387-413.)
© RSNA, 2002
From the Archives of the AFIP
Benign Tumors and Tumorlike Lesions of the Gallbladder and Extrahepatic Bile Ducts: Radiologic-Pathologic Correlation1
Angela D. Levy, LTC, MC, USA,
Linda A. Murakata, CDR, MC, USN,
Robert M. Abbott, LTC, USAF, MC and
Charles A. Rohrmann, Jr, MD
1 From the Departments of Radiologic Pathology (A.D.L.) and Hepatic and Gastrointestinal Pathology (L.A.M.), Armed Forces Institute of Pathology, Room M-121, Alaska and Fern Sts, NW, Washington, DC 20306-6000; Department of Radiology and Nuclear Medicine, Uniformed Services University of the Health Sciences, Bethesda, Md (A.D.L., R.M.A); Department of Radiology, Wilford Hall Medical Center, Lackland Air Force Base, San Antonio, Tex (R.M.A.); and Department of Radiology, University of Washington, Seattle (C.A.R.). Received August 15, 2001; revision requested September 24 and received October 17; accepted October 19. Address correspondence to A.D.L. (e-mail: levya@afip.osd.mil).
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Abstract
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A diverse spectrum of benign tumors and tumorlike lesions arises from the gallbladder and bile ducts, and despite their diversity, these lesions share common embryologic origins and histologic characteristics. Although these lesions are relatively uncommon, their importance lies in their ability to mimic malignant lesions in these locations. Benign neoplasms are derived from the epithelial and nonepithelial structures that compose the normal gallbladder and bile ducts. The epithelium gives rise to adenomas, cystadenomas, and the unusual condition of biliary papillomatosis. Granular cell tumors, neurofibromas, ganglioneuromas, paragangliomas, and leiomyomas are examples of benign tumors that may originate from nonepithelial structures. Tumorlike lesions are more commonly found in the gallbladder and include xanthogranulomatous cholecystitis, adenomyomatous hyperplasia, cholesterol polyps, and heterotopias. In the clinical setting of a patient with nonspecific abdominal complaints or symptoms of biliary obstruction, the discovery of a gallbladder or bile duct polyp or mass, gallbladder wall thickening, or biliary stricture is most often indicative of malignancy. However, the differential diagnosis should include benign tumors and tumorlike lesions. The preoperative determination of a benign lesion may significantly alter therapy and patient prognosis.
Index Terms: Bile ducts, neoplasms, 768.31 • Gallbladder, neoplasms, 768.31
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LEARNING OBJECTIVES FOR TEST 6
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After reading this article and taking the test, the reader will be able to:
- Identify the radiologic and pathologic features of benign tumors of the gallbladder and bile ducts.
- Describe the radiologic spectrum of tumorlike lesions of the gallbladder.
- Discuss the differential diagnosis of polypoid and infiltrating masses of the gallbladder and bile ducts.
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Introduction
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There is a diverse histologic spectrum of neoplasms that arise in the gallbladder and extrahepatic bile ducts. The gallbladder and extrahepatic bile ducts share this histologic diversity, since they have common embryologic origins. However, many of these neoplasms have remarkably different epidemiology and clinical manifestations. Although benign tumors of the gallbladder and bile ducts are uncommon, they are a challenge to the radiologist and surgeon because of the complex anatomic relationships that these structures share with adjacent vital organs. In addition, there are a number of nonneoplastic tumorlike lesions that should be considered in the differential diagnosis of a gallbladder or bile duct mass, polyp, focal wall thickening, or stricture.
Knowledge of the characteristics of benign tumors and tumorlike lesions of the gallbladder and bile ducts is important because they frequently mimic the more ominous malignant neoplasms that develop in these locations. This article reviews the clinical, pathologic, and radiologic features of benign tumors and tumorlike lesions of the gallbladder and bile ducts.
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Embryologic Development
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The gallbladder, bile ducts, and liver begin to develop during the 4th week of embryogenesis as a ventral bud from the most caudal aspect of the foregut (the future duodenum). This bud is called the hepatic diverticulum, and it grows between the layers of the ventral mesentery (Fig 1). The hepatic diverticulum has two distinct components: pars hepatica and pars cystica (1). The pars hepatica, the most cranial component, gives rise to the liver, common hepatic duct, and intrahepatic bile ducts. The pars cystica, the most caudal component, gives rise to the cystic diverticulum. The cystic diverticulum is the anlage of the gallbladder and the cystic duct. The original hepatic diverticulum elongates to form the common bile duct. These structures begin as solid cords, but by the 8th week of gestation, a lumen has been established throughout the biliary tract.
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Figure 1. Drawing of the normal embryologic development of the gallbladder and bile ducts illustrates the foregut (A), the cranial end of the hepatic diverticulum, which represents pars hepatica (B) and the cystic diverticulum (C). The ventral (D) and dorsal (E) pancreas are also demonstrated.
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The normal gallbladder wall is composed of four layers: the mucosa, which is composed of a single layer of columnar epithelium with an underlying basement membrane and lamina propria; an irregular smooth muscle layer; perimuscular connective tissue; and serosa. The mucosa forms primary and secondary folds when the gallbladder is empty and flattens as the lumen expands. There is no proper muscularis mucosa, submucosa, or muscularis propria. The outer perimuscular connective tissue contains large nerves, blood vessels, lymphatics, and occasional paraganglia. Along the hepatic surface there is no serosa (Fig 2), but occasional aberrant bile ducts (Luschka ducts) may be seen, usually surrounded by fibrous tissue. Thus, there is continuity of the connective tissue layer of the gallbladder with the interlobular connective tissue of the liver.
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Figure 2. Normal histologic characteristics of the gallbladder. Photomicrograph (original magnification, x2; hematoxylin-eosin [H-E] stain) shows the mucosa as a single layer of columnar epithelium (solid arrow) with an underlying lamina propria, irregular muscle layer (open arrow), and loose perimuscular connective tissue (*). Note the absence of a serosa in this section of the gallbladder, which was taken from the hepatic margin.
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The intrahepatic bile ducts are located in portal triads and are lined by cuboidal epithelial cells that rest on a basement membrane surrounded by dense fibrous connective tissue. The extrahepatic bile ducts are lined by a single layer of columnar epithelium that rests on a basement membrane above a dense connective tissue wall containing collagen, some elastic fibers, and groups of smooth muscle cells (Fig 3). The epithelial lining may be flat or pleated and contains less mucin than the gallbladder. The wall may contain small lobules of mucus glands (peribiliary glands) that drain into the saccule of Beale. The muscle layer is more prominent near the cystic duct, where it forms the valves of Heister, and near the sphincter of Oddi in the distal common bile duct. The subserosa contains adipose tissue, large blood vessels, lymphatics, and occasional ganglion cells.
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Figure 3. Normal histologic characteristics of the extrahepatic bile duct. Photomicrograph (original magnification, x4; H-E stain) shows the epithelium as a single layer of columnar cells (arrow) with an underlying dense connective tissue wall.
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Tumor Classification
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The World Health Organization classifies gallbladder and biliary tumors on the basis of their light microscopic and immunohistochemical features (2). Benign tumors may develop from the epithelial or nonepithelial layers of the gallbladder and bile ducts, giving rise to a spectrum of clinical, pathologic, and radiologic features. A number of tumorlike lesions that arise in the gallbladder and bile ducts have gross pathologic and radiologic features that resemble those of neoplasms. The Table lists the benign tumors and tumorlike lesions occurring in the gallbladder and bile ducts that have radiologic manifestations.
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Benign Tumors and Tumorlike Lesions of the Gallbladder and Extrahepatic Bile Ducts That Have Radiologic Manifestations
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Benign Epithelial Tumors
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Gallbladder Adenomas
Clinical and Pathologic Features.—
Adenomas of the biliary tract are uncommon. Gallbladder adenomas are found in 0.5% of cholecystectomy specimens (3). Familial adenomatous polyposis and Peutz-Jeghers syndrome are associated with an increased prevalence of adenomas of the gallbladder and biliary tract (4,5).
Gallbladder adenomas occur primarily in women, with a reported female-to-male ratio of 2.4:1 (6). Adenomas are usually asymptomatic and discovered incidentally during a radiologic evaluation for abdominal pain. Chronic or intermittent right upper quadrant pain may occur in patients with large adenomas or with adenomas that obstruct the cystic duct. A small proportion of gallbladder adenomas progress to carcinoma.
Gallbladder adenomas can be classified histologically as tubular, papillary, or tubulopapillary. The tubular adenoma is the most common variant (Fig 4a). It is covered by biliary epithelium and is composed of pyloric- or intestinal-type glands. In the former, cuboidal or columnar cells containing vesicular or hyperchromatic nuclei line the pyloric-type glands. In the latter, pseudostratified columnar epithelium lines the tubular intestinal-type glands. Papillary adenomas are composed of papillary structures lined by cuboidal or columnar cells (Fig 4b). The term tubulopapillary is used when both tubular glands and papillary structures each contribute to more than 20% of the tumor (6).
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Figure 4a. (a) Tubular adenoma of the gallbladder. Photomicrograph (original magnification, x4; H-E stain) shows a fibrovascular core lined by pyloric-type glands. (b) Papillary adenoma of the gallbladder. Photomicrograph (original magnification, x2; H-E stain) shows fingerlike processes lined by intestinal-type epithelium.
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Figure 4b. (a) Tubular adenoma of the gallbladder. Photomicrograph (original magnification, x4; H-E stain) shows a fibrovascular core lined by pyloric-type glands. (b) Papillary adenoma of the gallbladder. Photomicrograph (original magnification, x2; H-E stain) shows fingerlike processes lined by intestinal-type epithelium.
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At gross pathologic examination, gallbladder adenomas appear as polypoid structures that project into the gallbladder lumen and that may be sessile or pedunculated (Fig 5a). They are generally less than 2 cm in size. Approximately 10% of adenomas are multiple (7). The majority of cases (50%–65%) are associated with cholelithiasis (8). Tubular adenomas are typically lobular in contour, whereas papillary adenomas have a cauliflowerlike appearance.
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Figure 5a. Tubular adenoma of the gallbladder in a 67-year-old man with chronic right upper quadrant pain. (a) Photograph of the opened resected specimen shows a multilobulated, sessile, tan polyp attached to the gallbladder wall (straight arrow). Multiple gallstones are also present (curved arrow). (b) Longitudinal ultrasonographic (US) image shows an echogenic, lobulated, sessile polyp attached to the anterior wall of the gallbladder. The stones in the gross specimen were not identified in this imaging plane.
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Figure 5b. Tubular adenoma of the gallbladder in a 67-year-old man with chronic right upper quadrant pain. (a) Photograph of the opened resected specimen shows a multilobulated, sessile, tan polyp attached to the gallbladder wall (straight arrow). Multiple gallstones are also present (curved arrow). (b) Longitudinal ultrasonographic (US) image shows an echogenic, lobulated, sessile polyp attached to the anterior wall of the gallbladder. The stones in the gross specimen were not identified in this imaging plane.
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Radiologic Features.—
On US images, gallbladder adenomas are typically smoothly marginated, intraluminal polypoid masses. Occasionally, they may have a lobulated or cauliflowerlike contour. Sessile adenomas may have a broad base of attachment to the gallbladder wall, whereas pedunculated adenomas extend into to the lumen on a well-defined stalk. It may be necessary to scan the patient in the left lateral decubitus or prone position to visualize the stalk. The adjacent gallbladder wall characteristically maintains a normal thickness of less than 3 mm. Focal gallbladder wall thickening adjacent to a polypoid mass should raise concern for malignancy. The echotexture of adenomas is typically homogeneously hyperechoic (Fig 5b) (9); however, adenomas tend to be less echogenic and more heterogeneous as they increase in size (Fig 6). The additional finding of gallstones is common in patients with gallbladder adenomas.
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Figure 6. Papillary adenoma of the gallbladder in a 67-year-old man with right upper quadrant pain and a history of gallstones. Longitudinal US image of the gallbladder shows a medium echotexture mass (*) arising from the anterior wall of the gallbladder.
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At contrast material–enhanced computed tomography (CT), gallbladder adenomas appear as intraluminal soft-tissue masses that are iso- or hypoattenuating relative to the liver (10). They may be difficult to distinguish from noncalcified gallstones on CT scans, in which case US evaluation of the gallbladder may be helpful to determine whether the soft-tissue mass is a polyp or a stone.
Extrahepatic Bile Duct Adenomas
Clinical and Pathologic Features.—
Although the frequency of extrahepatic bile duct adenomas is not known, it is believed to be much lower than that of gallbladder adenomas. Because these lesions are rare, our current knowledge is based primarily on case reports. Patients with extrahepatic bile duct adenomas may present early with signs and symptoms of biliary obstruction, or the tumors may be found incidentally at surgery or during a radiologic evaluation of a patient with suspected gallbladder disease. The most common locations of biliary adenomas in descending order of frequency are the common bile duct, common hepatic duct, cystic duct, and intrahepatic bile ducts (7).
The majority of extrahepatic bile duct adenomas are tubular adenomas. They commonly are composed of intestinal-type glands (compared with the pyloric- and intestinal-type glands found in gallbladder adenomas) and are lined by pseudostratified columnar epithelium. Goblet cells, endocrine cells, and Paneth cells are frequently present within the epithelium. Papillary adenomas of the extrahepatic bile ducts also show intestinal differentiation and are commonly lined by mucin-containing columnar cells (7).
Radiologic Features.—
On US images, extrahepatic bile duct adenomas appear as intraluminal, nonshadowing masses that are isoechoic relative to liver parenchyma (Fig 7) (11,12). Proximal intra- and extrahepatic biliary dilatation may also be present. Tumefactive sludge may have a sonographic appearance similar to that of these tumors; therefore, altering the patient position during the US examination may be helpful in distinguishing an intraluminal polypoid mass from sludge. If the adenoma is located in the distal common bile duct, it may simulate a pancreatic or ampullary mass at US and CT.
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Figure 7. Tubular adenoma of the extrahepatic bile duct in a 46-year-old man with jaundice. Longitudinal US image of the common hepatic duct shows duct dilatation and a lobulated, mixed echotexture, intraluminal polypoid mass (arrow).
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At direct cholangiography (endoscopic retrograde cholangiopancreatography [ERCP] or percutaneous cholangiography), a biliary adenoma appears as a polypoid filling defect within the bile duct. The contour of the filling defect may be smooth and lobular in the case of tubular adenomas or cauliflowerlike in the case of papillary adenomas. Tumors that produce abundant mucin may manifest as a mucus cast at cholangiography (Fig 8).
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Figure 8a. Mucin-secreting extrahepatic bile duct adenoma in a 58-year-old woman with obstructive jaundice. (a) Endoscopic retrograde cholangiopancreatogram (ERCP) shows a castlike filling defect from mucin accumulation in the extrahepatic bile duct. (b) ERCP image obtained after balloon extraction of the mucus cast shows a lobulated sessile adenoma in the common hepatic duct (arrow).
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Figure 8b. Mucin-secreting extrahepatic bile duct adenoma in a 58-year-old woman with obstructive jaundice. (a) Endoscopic retrograde cholangiopancreatogram (ERCP) shows a castlike filling defect from mucin accumulation in the extrahepatic bile duct. (b) ERCP image obtained after balloon extraction of the mucus cast shows a lobulated sessile adenoma in the common hepatic duct (arrow).
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The principal radiologic differential diagnosis is adenocarcinoma of the bile duct. Ancillary findings of hepatoduodenal ligament adenopathy and tumor extension into adjacent structures are helpful diagnostic features of malignancy.
Biliary Papillomatosis
Clinical and Pathologic Features.—
Biliary papillomatosis is a rare disorder that was first described by Caroli and colleagues in 1959 (13). It is characterized by multiple and recurrent papillary adenomas in the biliary tract. The extrahepatic bile ducts are involved in the majority of cases. The intrahepatic bile ducts, cystic duct, gallbladder, and pancreatic duct may also be affected. Occasionally, the process involves only the intrahepatic ducts (14).
The majority of patients present for medical attention between the ages of 50 and 60 years, and men and women are equally affected (7). Patients present with signs and symptoms of biliary obstruction that is often complicated by cholangitis (15). Complete surgical excision of biliary papillomatosis is difficult and local recurrence is common. Some authors regard this lesion as a form of low-grade intraductal carcinoma (7). Papillomatosis has a greater potential for malignant transformation than a solitary adenoma.
Biliary papillomatosis is histologically characterized by biliary duct dilatation and multiple papillary adenomas. The epithelium of the papillary adenomas is composed of mucin-secreting columnar or cuboidal cells with basal nuclei. A fibrovascular core supports the epithelium (Fig 9a). Complex glandular structures (representing in situ carcinoma) and occasionally papillary carcinoma may be present.
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Figure 9a. Biliary papillomatosis in a 65-year-old man who presented with jaundice and sepsis. (a) Photomicrograph (original magnification, x2; H-E stain) shows multiple papillary projections lining the bile duct wall. (b) Photograph of the cut surface of the autopsy liver specimen shows multiple, tan, cauliflowerlike polyps within dilated intrahepatic bile ducts (arrows). There is fibrosis and thickening of the bile duct walls.
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Figure 9b. Biliary papillomatosis in a 65-year-old man who presented with jaundice and sepsis. (a) Photomicrograph (original magnification, x2; H-E stain) shows multiple papillary projections lining the bile duct wall. (b) Photograph of the cut surface of the autopsy liver specimen shows multiple, tan, cauliflowerlike polyps within dilated intrahepatic bile ducts (arrows). There is fibrosis and thickening of the bile duct walls.
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At gross inspection, the affected bile ducts are dilated. The bile duct walls may appear thickened and fibrotic. Intraluminal mucin may be visible. The papillary adenomas are typically tan, soft, and friable polyps (14) and usually do not demonstrate gross invasion of the bile duct wall (Fig 9b). Tumors that produce a significant amount of mucin may have a doughy or jellylike consistency (16).
Radiologic Features.—
The most common sonographic feature of biliary papillomatosis is intra- and extrahepatic biliary dilatation. Single or multiple, nonshadowing, medium echotexture, intraluminal masses may be visualized (16–18). Low-level echoes within the lumen of the bile ducts may represent mucin, sludge, or debris. Occasionally, sloughed tumor fragments may be seen as mobile masses within the bile ducts.
CT images of biliary papillomatosis in the liver and biliary tree also demonstrate intra- and extrahepatic duct dilatation. Hypoattenuating intraductal soft-tissue masses may be seen before and after intravenous administration of contrast material.
To our knowledge, the magnetic resonance (MR) imaging findings of biliary papillomatosis have been described in only two case reports in the literature (18,19). The lesions of biliary papillomatosis are low signal intensity on T1-weighted images and slightly hyperintense on T2-weighted images. The lesions do not significantly enhance following administration of gadolinium and remain hypointense relative to the adjacent liver parenchyma.
At direct cholangiography, biliary papillomatosis classically appears as multiple, irregularly marginated, polypoid filling defects within dilated intra- and extrahepatic bile ducts (Fig 10) (17,18).Irregular, granular, or shaggy margins of the bile duct walls may represent small adenomas or inflammatory changes from secondary cholangitis (Fig 10b). Lack of mobility during irrigation may help distinguish the papillary adenomas from intraductal stones or mucous plugs. Focal areas of biliary obstruction may be present.
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Figure 10a. Cholangiographic features of biliary papillomatosis. (a) Intraoperative cholangiogram of a 65-year-old man with jaundice shows multiple, polypoid filling defects in dilated intra- and extrahepatic bile ducts (straight arrows). The filling defect in the left hepatic duct (curved arrow) prevents contrast material filling of the left intrahepatic ducts. (b) ERCP image of a 75-year-old man with recurrent biliary papillomatosis shows multiple filling defects in a dilated common bile duct (solid arrows). There is irregularity and granularity of the distal common duct walls (open arrow).
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Figure 10b. Cholangiographic features of biliary papillomatosis. (a) Intraoperative cholangiogram of a 65-year-old man with jaundice shows multiple, polypoid filling defects in dilated intra- and extrahepatic bile ducts (straight arrows). The filling defect in the left hepatic duct (curved arrow) prevents contrast material filling of the left intrahepatic ducts. (b) ERCP image of a 75-year-old man with recurrent biliary papillomatosis shows multiple filling defects in a dilated common bile duct (solid arrows). There is irregularity and granularity of the distal common duct walls (open arrow).
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Biliary Cystadenomas
Clinical and Pathologic Features.—
Biliary cystadenomas are uncommon unilocular or multilocular cystic neoplasms that may occur within the liver, extrahepatic biliary tree, or gallbladder. Although biliary cystadenomas are benign tumors, they may recur after excision and have potential to develop into biliary cystadenocarcinoma (20,21). Cystadenomas occur predominantly in middle-aged women (average age, 42–55 years) (22–24). The clinical presentation is variable, depending on the size and location of the cyst. Abdominal pain, obstructive jaundice, palpable mass, increasing abdominal girth, nausea, and vomiting are common signs and symptoms. Occasionally, biliary cystadenomas may be incidentally discovered when the abdomen is imaged for other reasons.
Cystadenomas occur less commonly in the extrahepatic biliary system and gallbladder than in the liver. In the series reported by Devaney et al (22), 83% of cases were located within the liver, 13% were in the extrahepatic bile ducts (common bile duct, common hepatic duct, and cystic duct), and only one case (0.02%) was in the gallbladder.
At histologic analysis, cystadenomas have multiple loculations lined by cuboidal or columnar epithelium that resembles biliary epithelium. Only in rare cases are they unilocular. Underlying the epithelium, there is a highly cellular, mesenchymal, "ovarianlike" stroma and an outer layer of hyalinized fibrous tissue (Fig 11) (7). Goblet cells, Paneth cells, and scattered argyrophilic endocrine cells may be present in the epithelium. Ten percent to 15% of cystadenomas lack ovarian stroma. Approximately 13% of cystadenomas demonstrate dysplastic changes, findings that suggest that some may progress to carcinoma (22).
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Figure 11. Biliary cystadenoma. Photomicrograph (original magnification, x50; H-E stain) shows the cyst wall lined by benign cuboidal epithelium (arrow) with a subepithelial mesenchymal "ovarianlike" stroma.
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At gross pathologic examination, cystadenomas are well-defined cystic masses that may contain serous, mucinous, bilious, hemorrhagic, or mixed fluid (23). The outer wall is fibrous and the inner surface of the cyst may be smooth, granular, or trabeculated. Polypoid excrescences and septations may be seen extending into the lumen of the loculi (7).
Radiologic Features.—
Biliary cystadenomas range in size from 3 to 40 cm (23). Large cystadenomas may demonstrate mass effect on adjacent organs or may be associated with hepatomegaly, which will be apparent on abdominal radiographs (Fig 12). Abdominal radiographs may also demonstrate curvilinear calcification that may be present in the septa or cyst wall.
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Figure 12. Biliary cystadenoma in a 45-year-old woman who presented with complaints of abdominal fullness. Abdominal radiograph shows a soft-tissue opacity in the upper to mid abdomen that displaces the stomach and transverse colon.
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At US, a biliary cystadenoma appears as a unilocular or multilocular cyst with enhanced through transmission. Acoustic shadowing may be present from septal or wall calcification. The cyst fluid may contain low-level echoes from blood products, mucin, or proteinaceous fluid. Serous and bilious cyst fluid is generally anechoic. Echogenic mural nodules and papillary projections may be present (Fig 13).
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Figure 13a. US features of biliary cystadenoma. (a) Transverse US image of the liver in a 43-year-old woman with a biliary cystadenoma shows a well-defined anechoic cyst with enhanced through transmission. There are multiple echogenic tumor excrescences extending into the cyst lumen (arrows). (b) Transverse US image of the left hepatic lobe in a 52-year-old woman shows a complex anechoic cyst containing echogenic septa (straight arrow) and tumor nodules (curved arrow). (c) Transverse US image of the liver in a 55-year-old woman shows a biliary cystadenoma composed of complex fluid containing diffuse low-level internal echoes. Echogenic septa course through the complex fluid. A portion of the cystadenoma (*) contains simple anechoic fluid.
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Figure 13b. US features of biliary cystadenoma. (a) Transverse US image of the liver in a 43-year-old woman with a biliary cystadenoma shows a well-defined anechoic cyst with enhanced through transmission. There are multiple echogenic tumor excrescences extending into the cyst lumen (arrows). (b) Transverse US image of the left hepatic lobe in a 52-year-old woman shows a complex anechoic cyst containing echogenic septa (straight arrow) and tumor nodules (curved arrow). (c) Transverse US image of the liver in a 55-year-old woman shows a biliary cystadenoma composed of complex fluid containing diffuse low-level internal echoes. Echogenic septa course through the complex fluid. A portion of the cystadenoma (*) contains simple anechoic fluid.
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Figure 13c. US features of biliary cystadenoma. (a) Transverse US image of the liver in a 43-year-old woman with a biliary cystadenoma shows a well-defined anechoic cyst with enhanced through transmission. There are multiple echogenic tumor excrescences extending into the cyst lumen (arrows). (b) Transverse US image of the left hepatic lobe in a 52-year-old woman shows a complex anechoic cyst containing echogenic septa (straight arrow) and tumor nodules (curved arrow). (c) Transverse US image of the liver in a 55-year-old woman shows a biliary cystadenoma composed of complex fluid containing diffuse low-level internal echoes. Echogenic septa course through the complex fluid. A portion of the cystadenoma (*) contains simple anechoic fluid.
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The CT attenuation of the fluid component in a biliary cystadenoma varies depending on the fluid content. Higher attenuation may indicate recent hemorrhage. Calcifications that may be present in the septa or cyst wall are typically more apparent with CT than other imaging modalities (Fig 14). Septa may enhance with contrast material (Fig 15). Tumor nodules and papillary projections appear as soft-tissue attenuation nodules that typically enhance with contrast material. Occasionally, CT does not demonstrate thin septations that are visualized with US (25). The MR signal intensity of biliary cystadenoma is variable on both T1- and T2-weighted images, depending on the content of the cyst fluid (Fig 16) (24,26).
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Figure 14a. Biliary cystadenoma in a 55-year-old woman with abdominal pain and jaundice. (a, b) Contrast-enhanced CT scans (a at a more cephalic level than b) show a multilocular cyst with septations and mural calcifications (straight arrow) in the left hepatic lobe. There is biliary duct dilatation and extension of the cyst into the left hepatic and common bile ducts (curved arrow). (c) Photograph of the bisected specimen shows the smooth inner surface of the cyst with multiple loculi and septations.
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Figure 14b. Biliary cystadenoma in a 55-year-old woman with abdominal pain and jaundice. (a, b) Contrast-enhanced CT scans (a at a more cephalic level than b) show a multilocular cyst with septations and mural calcifications (straight arrow) in the left hepatic lobe. There is biliary duct dilatation and extension of the cyst into the left hepatic and common bile ducts (curved arrow). (c) Photograph of the bisected specimen shows the smooth inner surface of the cyst with multiple loculi and septations.
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Figure 14c. Biliary cystadenoma in a 55-year-old woman with abdominal pain and jaundice. (a, b) Contrast-enhanced CT scans (a at a more cephalic level than b) show a multilocular cyst with septations and mural calcifications (straight arrow) in the left hepatic lobe. There is biliary duct dilatation and extension of the cyst into the left hepatic and common bile ducts (curved arrow). (c) Photograph of the bisected specimen shows the smooth inner surface of the cyst with multiple loculi and septations.
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Figure 15a. Biliary cystadenoma in a 40-year-old woman with right upper quadrant pain. (a) Contrast-enhanced CT scan shows a well-defined water-attenuation cyst with enhancing loculi (arrow) in the left hepatic lobe. (b) Photograph of the cut resected left lobe shows the fibrous wall of the cystadenoma, multiple tumor nodules (curved arrow), and loculi. The mass arises from the compressed bile duct (straight arrow).
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Figure 15b. Biliary cystadenoma in a 40-year-old woman with right upper quadrant pain. (a) Contrast-enhanced CT scan shows a well-defined water-attenuation cyst with enhancing loculi (arrow) in the left hepatic lobe. (b) Photograph of the cut resected left lobe shows the fibrous wall of the cystadenoma, multiple tumor nodules (curved arrow), and loculi. The mass arises from the compressed bile duct (straight arrow).
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Figure 16a. Biliary cystadenoma in a 50-year-old woman who presented with increasing abdominal girth and jaundice. (a) Contrast-enhanced CT scan shows a large multilocular cyst that contains fluid of high (*) and low attenuation, mural calcifications, and septa. Biliary dilatation is present. (b) T1-weighted MR image shows high-signal-intensity mucoid fluid in the large loculus (*) and low-signal-intensity serous fluid in the smaller loculi. Intermediate-signal-intensity fluid is also present. (c) T2-weighted MR image shows the mucoid fluid as low signal intensity (*) and the remainder of the loculi containing high-signal-intensity fluid. The septations within the cystadenoma are more prominent on the T2-weighted image.
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Figure 16b. Biliary cystadenoma in a 50-year-old woman who presented with increasing abdominal girth and jaundice. (a) Contrast-enhanced CT scan shows a large multilocular cyst that contains fluid of high (*) and low attenuation, mural calcifications, and septa. Biliary dilatation is present. (b) T1-weighted MR image shows high-signal-intensity mucoid fluid in the large loculus (*) and low-signal-intensity serous fluid in the smaller loculi. Intermediate-signal-intensity fluid is also present. (c) T2-weighted MR image shows the mucoid fluid as low signal intensity (*) and the remainder of the loculi containing high-signal-intensity fluid. The septations within the cystadenoma are more prominent on the T2-weighted image.
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Figure 16c. Biliary cystadenoma in a 50-year-old woman who presented with increasing abdominal girth and jaundice. (a) Contrast-enhanced CT scan shows a large multilocular cyst that contains fluid of high (*) and low attenuation, mural calcifications, and septa. Biliary dilatation is present. (b) T1-weighted MR image shows high-signal-intensity mucoid fluid in the large loculus (*) and low-signal-intensity serous fluid in the smaller loculi. Intermediate-signal-intensity fluid is also present. (c) T2-weighted MR image shows the mucoid fluid as low signal intensity (*) and the remainder of the loculi containing high-signal-intensity fluid. The septations within the cystadenoma are more prominent on the T2-weighted image.
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Cholangiography (ERCP or percutaneous cholangiography) may be a helpful adjunct in the evaluation of a patient with a suspected biliary cystadenoma when there is evidence of duct dilatation or obstruction at cross-sectional imaging. In a small percentage of cases, biliary cystadenomas may communicate with the biliary tree (Fig 17). In other instances, there may be an intraductal component (Fig 18) or extrinsic compression of the bile ducts as the cause of biliary obstruction.
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Figure 17. Biliary cystadenoma in a 56-year-old woman who had no hepatobiliary symptoms. Lateral radiograph of the abdomen obtained after ERCP shows communication of the cystadenoma (arrow) with the biliary system. The gallbladder has an anterior location.
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Figure 18a. Biliary cystadenoma in a 39-year-old woman with an elevated bilirubin level. (a) Contrast-enhanced CT scan shows a small cyst in the region of the falciform ligament. There is dilatation of the left hepatic ducts (arrow). (b) ERCP image shows dilatation of the left hepatic and common ducts. There is a filling defect (arrow) in the common duct from intraductal extension of the cystadenoma. (c) Photograph of the resected surgical specimen shows the opened biliary cystadenoma (*) with a polypoid component (straight arrow) extending into the opened common hepatic duct.
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Figure 18b. Biliary cystadenoma in a 39-year-old woman with an elevated bilirubin level. (a) Contrast-enhanced CT scan shows a small cyst in the region of the falciform ligament. There is dilatation of the left hepatic ducts (arrow). (b) ERCP image shows dilatation of the left hepatic and common ducts. There is a filling defect (arrow) in the common duct from intraductal extension of the cystadenoma. (c) Photograph of the resected surgical specimen shows the opened biliary cystadenoma (*) with a polypoid component (straight arrow) extending into the opened common hepatic duct.
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Figure 18c. Biliary cystadenoma in a 39-year-old woman with an elevated bilirubin level. (a) Contrast-enhanced CT scan shows a small cyst in the region of the falciform ligament. There is dilatation of the left hepatic ducts (arrow). (b) ERCP image shows dilatation of the left hepatic and common ducts. There is a filling defect (arrow) in the common duct from intraductal extension of the cystadenoma. (c) Photograph of the resected surgical specimen shows the opened biliary cystadenoma (*) with a polypoid component (straight arrow) extending into the opened common hepatic duct.
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There are no specific imaging features that permit reliable differentiation of biliary cystadenoma from cystadenocarcinoma (23). The differential diagnosis principally includes hepatic echinococcal cyst, hepatic abscess, and a hemorrhagic bile duct cyst. In rare cases, other neoplasms such as mesenchymal hamartoma, undifferentiated embryonal sarcoma, cystic hepatocellular carcinoma, and cystic metastasis may have a similar appearance. Correlation of imaging findings with patient age and clinical data may be helpful in the differential diagnosis.
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Nonepithelial Tumors
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Granular Cell Tumors
Clinical and Pathologic Features.—
Granular cell tumors have been found in virtually every location in the body. The tongue is the single most common site of occurrence, but these tumors have been identified in the oropharynx, gastrointestinal tract, respiratory tract, breast, skin, and subcutaneous tissues. One percent of these tumors occur in the biliary tract.
Granular cell tumors account for 10% of benign biliary tumors. The most frequent location of these tumors in the biliary tree is the common bile duct (50% of cases), followed by the cystic duct (37%), common hepatic duct (11%), gallbladder (4%), and intrahepatic ducts (4%) (27). Ninety percent of patients are women, 76% of whom are African-American. The mean age at presentation is 34 years (27).
The clinical manifestation of these tumors is based on their location within the biliary system. When located in the common duct, these tumors typically manifest with painless jaundice caused by biliary obstruction. As a result, these tumors often initially mimic cholangiocarcinoma or focal sclerosing cholangitis (28). Patients with gallbladder or cystic duct granular cell tumor may present with biliary colic or acute cholecystitis. Although uncommon, this entity should be considered in the differential diagnosis of biliary tract disease in young patients, particularly African-American women (29).
There has been considerable debate about the histologic origin of granular cell tumor. First described in 1926 as granular cell myoblastoma, these tumors were thought to arise from striated muscle cells. It is now thought that granular cell tumor is of Schwann cell origin, since the tumor cells react with antibodies to the S-100 protein, which is normally found in the central nervous system and peripherally in Schwann cells.
Granular cell tumors are composed of large polygonal cells with eosinophilic granular cytoplasm and centrally located, small, dark and uniform nuclei (Fig 19). The cytoplasm reacts positively to the periodic acid-Schiff stain, and recently, immunoreactivity to inhibin has been demonstrated in granular cell tumor of the extrahepatic bile ducts (30). Use of frozen sections may not be reliable for establishing the diagnosis unless there is a high degree of suspicion for the diagnosis of granular cell tumor preoperatively (28,31).
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Figure 19. Granular cell tumor of the common bile duct. Photomicrograph (original magnification, x20; H-E stain) shows large polygonal cells with eosinophilic granular cytoplasm (arrow) below the biliary epithelium in the wall of the common bile duct.
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At gross examination, the tumors are usually nonencapsulated, are less than 3 cm in greatest dimension, and appear yellow-tan to yellow-white. As the cells infiltrate the wall of the bile duct, the lumen is obliterated (7).
Radiologic Features.—
Because granular cell tumors are so small, it may be difficult to depict them with US or CT. On US images, granular cell tumor is a heterogeneous, mildly hyperechoic, poorly defined mass that may have faint posterior acoustic shadowing (32). On CT scans, granular cell tumor is a nonspecific soft-tissue mass. Calcification is not typically seen with either US or CT; however, biliary duct dilatation is usually evident with both US and CT.
At direct cholangiography (ERCP or percutaneous cholangiography), granular cell tumor manifests as a short (1–3-cm) segment annular stricture (Fig 20) or abrupt obstruction of the extrahepatic bile ducts. Narrowing of the extrahepatic ducts, which maybe symmetric or eccentric, typically results from the intramural growth of the tumor. These stenotic areas are morphologically characterized by a smooth mucosa without irregularity, nodularity, or ulceration. Completely obstructing lesions are characterized by abrupt obstruction without areas of irregularity or ulceration (Fig 21). Although biliary granular cell tumor usually occurs as a solitary tumor, multifocal tumors have been reported (33,34). MR cholangiography, although not previously reported in conjunction with the diagnosis of granular cell tumor, has the added benefit of demonstrating both the intraluminal and extraluminal extent of disease in patients who present with biliary obstruction.
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Figure 20a. Granular cell tumor in a 27-year-old woman who presented with jaundice. (a) ERCP image shows a focal stricture in the distal common hepatic duct (arrow). (b) Photograph of the resected specimen shows marked mural thickening of the distal common hepatic duct (arrows). The gallbladder is reflected upward.
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Figure 20b. Granular cell tumor in a 27-year-old woman who presented with jaundice. (a) ERCP image shows a focal stricture in the distal common hepatic duct (arrow). (b) Photograph of the resected specimen shows marked mural thickening of the distal common hepatic duct (arrows). The gallbladder is reflected upward.
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Figure 21a. Granular cell tumor in a 30-year-old woman who presented with pruritis and jaundice. (a) Percutaneous transhepatic cholangiogram shows extrahepatic biliary dilatation with high-grade obstruction of the distal common bile duct (arrow). There is contrast material in the duodenum. (b) Photograph of the resected distal common bile duct and duodenum shows tumor infiltration (arrows) of the ductal wall with luminal narrowing. The probe indicates the papilla of Vater.
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Figure 21b. Granular cell tumor in a 30-year-old woman who presented with pruritis and jaundice. (a) Percutaneous transhepatic cholangiogram shows extrahepatic biliary dilatation with high-grade obstruction of the distal common bile duct (arrow). There is contrast material in the duodenum. (b) Photograph of the resected distal common bile duct and duodenum shows tumor infiltration (arrows) of the ductal wall with luminal narrowing. The probe indicates the papilla of Vater.
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Neurofibromas and Neurofibromatosis
Clinical and Pathologic Features.—
Neurofibromas of the gallbladder and bile ducts are distinctly uncommon and are usually associated with neurofibromatosis. There are only a handful of case reports in the literature of neurofibromas occurring in the gallbladder in patients without neurofibromatosis (35–37). All of these patients presented with symptoms of right upper abdominal pain.
Involvement of the gallbladder and biliary tract in type 1 neurofibromatosis is an uncommon gastrointestinal manifestation. Gastrointestinal involvement occurs in 25% of patients with neurofibromatosis. Gastrointestinal dysmotility with hyperplasia of the intestinal myenteric and submucosal plexuses, mucosal ganglioneuromatosis, and gastrointestinal stromal tumors are the more common manifestations (38). Biliary involvement is usually secondary to obstructing duodenal and periampullary neuroendocrine tumors (39).
Neurofibromas of the gallbladder have been described as intraluminal polypoid masses or intramural nodules (7). The histologic characteristics of neurofibromas of the gallbladder and bile ducts do not differ from those in other anatomic sites. The tumors are composed of spindle-shaped cells with wavy nuclei (Fig 22). The spindle-shaped cells are organized into fascicles and stain focally positive for S-100 protein. There are areas within the tumor that have loose stromal tissue with a mucin-rich matrix.
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Figure 22. Neurofibroma. Photomicrograph (original magnification, x50; H-E stain) shows spindle-shaped cells (arrow) in a moderately cellular area adjacent to an area with loose mucin-rich matrix.
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Radiologic Features.—
The imaging features of neurofibromas of the gallbladder have been described only in isolated case reports. The US and CT findings of a soft-tissue intraluminal mass correspond to the gross pathologic features of a polypoid intraluminal mass. To our knowledge, there are no descriptions of the radiologic features of neurofibromas of the bile ducts. We have seen one case of plexiform neurofibromas in a patient with type 1 neurofibromatosis that diffusely involved the extrahepatic and central intrahepatic bile ducts. In this case, a low-attenuation tubular mass paralleled the intra- and extrahepatic bile ducts (Fig 23).
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Figure 23a. Plexiform bile duct neurofibroma in a 44-year-old man with neurofibromatosis type 1 who presented with uncontrolled hypertension. Contrast-enhanced CT scans (a at a more cephalic level than b) show a low-attenuation mass paralleling the intra- and extrahepatic bile ducts (solid arrow). The patient also has a pheochromocytoma of the right adrenal gland (open arrow in b).
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Abstract
LEARNING OBJECTIVES FOR TEST...
