A Hybrid Peripheral Nerve Sheath Tumor (Granular Cell Tumor + Schwannoma) of Cystic Duct Origin, Presenting with Gallbladder Enlargement and Abdominal Pain

Granular cell tumors and schwannomas rarely occur in cystic ducts. We herein report a case of a hybrid tumor consisting of a cystic duct-originating granular cell tumor and schwannoma. A 48-year-old woman was referred to our hospital with the chief complaint of occasional postprandial abdominal pain after an enlarged gallbladder was found on ultrasonography. The cause was identified as a mass measuring approximately 7 mm in diameter in the cystic duct, and the patient underwent extrahepatic cholangiectomy. An examination of the surgical specimen revealed that the mass originated from the cystic duct and narrowed the duct lumen. Histopathologically, both granular cell tumors and schwannoma components were detected. To our knowledge, this is the first report of a hybrid peripheral nerve sheath tumor with a mixture of granuloma cell tumors and schwannomas.