Extrahepatic biliary cystadenocarcinoma arising from the left hepatic duct.

A 54-year-old man, who had no clinical symptoms, underwent a routine health checkup at our hospital. Abdominal ultrasonography disclosed a well demarcated tumor containing a solid portion occupying the dilated left hepatic duct and a cystic portion expanding into the parenchyma of the left hepatic lobe, with mild dilatation of the intrahepatic bile ducts. These findings were later confirmed by computed tomography (CT) and magnetic resonance imaging. Endoscopic retrograde cholangiography revealed a complete defect at the level of the left hepatic duct, while drip infusion cholangiographic-CT (DIC-CT) disclosed a defect of the left hepatic duct only, with the distal portions of the left intrahepatic ducts being visualized on the image. Hepatic angiography revealed light stains in the solid portion in the parenchymal phase. At left lobectomy, a multiloculated polyp-like tumor was found arising from the left hepatic duct and expanding into the parenchyma of the left hepatic lobe. Microscopically, all the lining cells in the cysts and the tumor cells in the solid portion showed the features of papillary adenocarcinoma. In this patient with extrahepatic biliary cystadenocarcinoma, DIC-CT was useful in identifying the site of origin of the tumor, and hepatic angiography was also useful in differentiating this rare malignant tumor from benign cystadenoma.