Intrahepatic biliary papillomatosis arising in nonobstructive intrahepatic biliary dilatations confined to the hepatic left lobe.

Papillomatosis of intrahepatic bile ducts is a rare pathologic entity. We describe herein a case of papillomatosis of intrahepatic bile ducts associated with nonobstructive dilatations of intrahepatic bile ducts of the hepatic left lobe. The patient, a 70-yr-old female, complained of right upper abdominal pain. Cholangiograms revealed multiple cystic dilatations of the left intrahepatic bile ducts. The right intrahepatic bile ducts were almost normal. The patient underwent left lobectomy of the liver. Grossly, intrahepatic bile ducts of the left lobe were cystically dilated and contained a little mucinous fluid. The inner surface of the dilated ducts was mildly granular or papillary. Microscopically, the walls of the dilated intrahepatic ducts were diffusely covered by columnar epithelial cells with papillary configurations. There was mild atypia of the epithelial cells, but no invasion of the epithelial cells into underlying duct walls was found. To the best of our knowledge, this is the first case of papillomatosis of intrahepatic bile ducts associated with nonobstructive dilatations of intrahepatic bile ducts confined to the left lobe. Although the pathogenesis of intrahepatic biliary papillomatosis of our case is unclear, it seems conceivable that biliary irritation associated with the nonobstructive dilatations of intrahepatic bile ducts is causally related to the papillary proliferations of intrahepatic bile duct epithelial cells.