A Rare Case of Intraductal Papillary Mucinous Neoplasm of the Biliary Duct in a Patient with Prostate Adenocarcinoma.

Intraductal papillary mucinous neoplasms (IPMNs) are mucin-producing papillary neoplasms of the pancreatic or biliary ductal system that exhibit variable cellular atypia and cause ductal dilation. There are few reported cases of IPMN arising from the biliary tree in the literature. It has a higher propensity to undergo malignant transformation compared to IPMN arising from the pancreatic duct. An 80-year-old male underwent cross-sectional tomography (CT) imaging of the abdomen for evaluation of prostate adenocarcinoma, which revealed an incidental 2.3 × 2.7 cm soft tissue mass centered at the porta hepatis with diffuse dilatation of the left intrahepatic biliary ductal system and mild prominence of the right intrahepatic ductal system. Endoscopic ultrasound showed 2 adjacent hilar masses involving the common hepatic duct and the left hepatic duct with protrusion of the tissue into the lumen of the duct and upstream ductal dilatation. Endoscopic retrograde cholangiopancreatography revealed a large filling defect in the common hepatic duct extending into the left hepatic duct. A large amount of clot and soft tissue with a fish-egg appearance was retrieved. The patient underwent left hepatic lobectomy, radical resection of the common hepatic duct with Roux-en-Y hepaticojejunostomy to the right hepatic duct. Histopathological examination of the resected specimen revealed intraductal papillary mucinous neoplasm with diffuse high-grade dysplasia. Follow-up CT scan of the abdomen 2 months after the surgery was negative for any masses.