Intraductal oncocytic papillary neoplasm of the liver.

A very rare case of intraductal oncocytic papillary carcinoma of the liver is reported. A 63-year-old Japanese man was admitted to our clinic because of abdominal pain and jaundice. Imaging techniques revealed a unilocular cystic neoplasm of 14 cm diameter in the medial segment of the left hepatic lobe. Combined percutaneous and endoscopic retrograde cholangiographies revealed the unilocular cystic neoplasm contained a lot of mucus and communicated with the left segmental intrahepatic bile duct, and that mucus filled the left segmental and hepatic ducts. Left lobectomy was performed. The postoperative course was good, and the patient is free of disease 30 months after operation. Pathological examination revealed that the cavity of the neoplasm was continuous with the left segmental intrahepatic bile duct, and that a lot of mucus was present in the neoplasm, as well as in the left segmental and hepatic ducts. The neoplasm consisted of papillary growth of atypical epithelial cells with oncocytic changes. Atypical goblet cells were also recognized. No invasion into the surrounding liver was noted. Non-tumorous intrahepatic bile ducts near the lesion occasionally showed epithelial dysplasia and contained a lot of mucus. Immunohistochemically, the tumor cells were rich in mitochondria and were immunoreactive for cytokeratins 7, 18 and 19, carbohydrate antigen 19-9, and hepatocyte-specific antigen. Some tumor cells were immunoreactive for pancreatic alpha-amylase and lipase. Ultrastructurally, the tumor cells showed numerous mitochondria and mucus droplets. Intraductal neoplasm communicating with the intrahepatic bile ducts has rarely been reported. The present case suggests that intraductal oncocytic papillary neoplasm, as described in the pancreas, may also occur in the intrahepatic bile ducts, and that such hepatic intraductal neoplasm may express hepatocellular and pancreatic acinar phenotypes.