A 76-year-old man was referred to the hospital because of stomach pain, vomiting, and fever persisting for a few days. On physical examination, there was no abdominal tenderness.
Initial blood tests revealed normal white cell count and elevated liver aminotransferases (aspartate aminotransferase = 427 U/L [normal range <32], alanine aminotransferase = 480 U/L [normal range <31]), elevated lactate dehydrogenase (827 U/L, normal range = 240-480), and gamma-glutamyl transferase (1328 U/L, normal range <35). Bilirubin was normal. At the emergency unit, computed tomography (CT) was performed showing an infiltrating mass with small rather linear calcifications in the right liver lobe extending through the main bile duct into the pancreatic head. (Fig. 1)
Magnetic resonance imaging (MRI) demonstrated a T2 hyperintense to intermediate intense, T1 hypointense, diffusion restrictive, complex solid neoplasm with a tubular aspect and slight contrast uptake, extending from the main bile duct into the right intrahepatic bile ducts. There is focal invasion into the cystic duct and the gallbladder. (Fig. 2)
The differential diagnosis includes biliary papillomatosis, polypoid cholangiocarcinoma and hepatocellular carcinoma with intraductal growth. Surgery was performed with peroperative histology of frozen samples showing papillary carcinoma. Paraffin embedded samples showed dysplastic epithelium of the bile ducts with diffuse papillary proliferations. There are atypical columnar cells and only slight development of fibrovascular structures. The epithelium shows ulcerations and a high grade of dysplasia with hyperchromatic nuclei and a large number of mitotic figures. There are foci of perineural extension and invasion of the connective tissue. The lumen is filled with mucus, blood remnants and tumoral debris.
The diagnosis of biliary papillomatosis of the bile ducts with malignant transformation into an invasive papillary carcinoma was made. (Fig. 3)
Caroli first described biliary papillomatosis in 1959.1 It has a 2:1 male-female ratio and the mean age at presentation lies in the seventh decade of life.2 Malignant transformation rates are high, varying between 41% and 83%.2-4 The pathogenesis of the disease is not yet known, but has been thought to be related to chronic biliary ductal inflammation from pancreatic juice reflux3 resulting in extensive proliferation of the bile duct epithelium followed by the dysplasia–carcinoma sequence.3, 4 It involves the intrahepatic and extrahepatic bile ducts but also the gallbladder. Lee et al.3 distinguished between lesions that secrete an excessive amount of mucus and those that do not.
Because the bile ducts are partially obstructed and the tumor fragments occlude the bile duct intermittently, clinical symptoms, signs and laboratory tests mimic those of bile duct stones.
Imaging is of major importance in the work-up and postsurgical evaluation. Ultrasound is nonspecific, showing dilated bile ducts, and endoscopic retrograde cholangiopancreaticography shows multiple rounded filling defects mimicking choledocholithiasis.
Both CT and MRI are useful in the initial staging of the tumor and in the subsequent postoperative follow-up. Although MR signal characteristics of biliary papillomatosis and cholangiocarcinoma overlap, showing a hypointense lesion at T1-weighted images and a hyperintense lesion at T2-weighted images without significant enhancement after Gd, both able to cause bile duct dilatation, lesions can be differentiated based on the fact that cholangiocarcinoma is more likely to invade vascular structures, especially in such a central location, and metastasize to local lymph nodes. Also the rounded configuration of the mass is a clue, which can help to diagnose biliary papillomatosis.5, 6
Treatment of this disease includes surgery (including liver transplantation), palliative stenting, drainage or ablation.1, 7 Curative surgical resection has a 5-year survival rate as high as 81%. In case of palliative drainage, the mean survival is 37 months.3
Although biliary papillomatosis is a rare condition, a high index of suspicion is required to diagnose because the high malignant potential.