Fine-needle aspiration cytologic diagnosis of intrahepatic biliary papillomatosis (intraductal papillary tumor): report of three cases and comparative study with cholangiocarcinoma.

Biliary papillomatosis is a rare tumor of the intrahepatic and extrahepatic biliary tree, and its FNA findings have not been reported. The cytologic features of 3 cases of intrahepatic biliary papillomatosis were studied and compared with 5 cases of cholangiocarcinoma. The distinctive features include: 1) hypercellular smear, 2) very broad and often double-cell layered sheets of ductal columnar epithelium, 3) papillary configuration, 4) preserved honeycomb pattern with even nuclear spacing, and 5) dysplastic but not frankly malignant nuclear features. The constellation of these features is highly characteristic of biliary papillomatosis and helpful in distinguishing it from cholangiocarcinoma and other differential diagnoses. A firm preoperative diagnosis can thus be achieved, allowing better planning in management of this borderline malignant tumor. Copyright 2000 Wiley-Liss, Inc.