Adenomyoma of the common hepatic duct mimicking bile duct cancer: report of a case.

We report an unusual case of adenomyoma of the common hepatic duct mimicking bile duct cancer. A 50-year-old woman was referred to our hospital for the investigation of general fatigue. Laboratory data showed abnormal liver test results and computed tomography showed a mass lesion in the hepatic hilum and dilatation of the intrahepatic bile ducts. These findings led to a preoperative diagnosis of hilar bile duct carcinoma, and we performed a left lobectomy with resection of the extrahepatic bile duct. Macroscopically, an elevated lesion was found in the common hepatic duct, which was confirmed histologically to be an adenomyoma. Bile duct strictures are rarely caused by benign tumors of the biliary tract, such as adenomyoma. Surgical resection of the bile duct should be considered for all bile duct strictures because it is often difficult to differentiate malignant from benign lesions in this location preoperatively, and malignant cells may be present in the lesion.