Extrahepatic biliary schwannoma.

Schwannoma (neurilemoma or neurinoma) rarely develops in the biliary tract. We report here a case of extrahepatic biliary schwannoma found in a 47-yr-old Japanese woman presenting with obstructive jaundice. The radiological imaging studies were suggestive of nonepithelial tumor involving the common bile duct. The patient underwent tumor resection. The tumor extended inward and outward from the wall of the common bile duct in the shape of a dumbbell. The extraductal tumor was solid with microcystic changes, while the intraductal lesion presented cystic changes. Microscopically, the tumor was predominantly composed of spindle-shaped cells with nuclear palisading, and it contained lymphoid aggregates. Immunohistochemically, the tumor cells were positive for S-100 protein. The final diagnosis was benign schwannoma of the common bile duct. The tumor differed from usual soft tissue schwannoma and closely resembled gastrointestinal schwannoma.