Cystic duct carcinoma in a 67-year-old male with abdominal pain.A mass lesion near the gallbladder was found on ultrasonography during an annual medical checkup. Laboratory test results, including tumor markers, were negative. Contrast-enhanced computed tomography demonstrates enhanced circumferential wall thickening in the cystic duct (arrow) with gallbladder enlargement. Open cholecystectomy was performed, and the lesion was diagnosed as cystic duct adenocarcinoma.