Granular cell tumor of the biliary tree. A report of two cases and a review of the literature.

Granular cell tumors are relatively uncommon soft tissue tumors usually presenting in the skin and subcutaneous tissues or tongue, although many sites have been described. Two cases arising in the extrahepatic biliary tree are described, and the previously reported cases of this rare presentation are reviewed. These tumors may mimic sclerosing cholangitis and cholangiocarcinoma clinically, and occasionally histologically, in this relatively young group of patients. The histogenesis appears to be related to Schwann cells as in granular cell tumors of other sites, evidenced by histologic, immunohistochemical, and electron microscopic findings. Granular cell tumors, albeit rare, should be considered in the differential diagnosis of biliary tract disease in young patients, particularly black women, and are curable by surgical excision.