Granular cell tumor: unusual cause for mucocele of gallbladder.

A small granular cell tumor of the cystic bile duct is presented. A review of the literature revealed that all previously reported granular cell tumors in the biliary ducts affected women. Among them, 13 cystic bile duct tumors were exclusively small and slow-growing benign lesions. All had been operated on for gallstone disease, but in 10 cases no stone was actually found. Although such a small tumor might be easily overlooked grossly, histological diagnosis is relatively easy if differentiated from a reactive smooth muscle granular lesion.