Granular cell tumor at the hepatic duct confluence mimicking Klatskin tumor. A report of two cases and a review of the literature

Granular cell tumors are rare tumors most often located in the oral cavity, skin or subcutaneous tissue. The occurrence of this tumor in the biliary tree is extremely rare. Two patients are described presenting with biliary obstruction due to a tumor at the hepatic duct confluence. One patient is a 38-year-old white male with concomitant cutaneous granular cell tumors, and the other a 50-year-old white female. Hilar excision was performed in both patients. Histopathology of the tumors revealed a proliferation of cells with granular cytoplasm, diagnosed as granular cell tumor. At preoperative examination, hilar granular cell tumors are difficult to differentiate from cholangiocarcinoma, sclerosing cholangitis or more common benign biliary tumors. Treatment consists of surgical excision after which prognosis is favorable.