Primary hepatoid carcinoma of the biliary tree: a radiologic mimicker of Klatskin-type tumor.

Hepatoid carcinomas are a group of neoplasms with features resembling hepatocellular carcinomas. Although extremely rare, more cases have been noted to arise from various organs within the last decade. Differentiating these tumors when located in the biliary tree from cholangiocarcinoma is not only a radiologic challenge but also critical, because treatment modalities and operative strategies are dependent on the exact nature of the tumor. We report a unique case in the literature of a 67-year-old Caucasian female who presented with obstructive jaundice due to an obstructing mass seen at the common hepatic duct on imaging with no preceding history of cirrhosis and increased serum α-fetoprotein (AFP), in whom a differential diagnosis from cholangiocarcinoma in a non-cirrhotic liver was particularly difficult given the combination of tumor location and solitary nature. The radiologist may include ectopic hepatoid adenocarcinomas in the differential consideration of an obstructing tumor in the biliary tree especially in patients with increased serum AFP levels.