A 64-year-old man presented with epigastric discomfort and nausea. Laboratory analyses revealed increased levels of total and direct bilirubin, and increased levels of aminotransferases. Computed tomography revealed the presence of a mass in the distal common bile duct. Endoscopic retrograde cholangiopancreatography and intraductal ultrasonography revealed a 25 mm filling defect in the distal common bile duct, and biopsy of the lesion disclosed the presence of tubular adenoma. Using fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET) revealed an increased accumulation of the tracer in the lesion, with a maximum standard uptake value (SUVmax) of 3.3. The patient received a pylorus-preserving pancreatoduodenectomy. The histopathological examination revealed a tubular adenoma with low-grade atypia. The patient remains alive 15 months following the surgery, with no evidence of recurrence of the adenoma. 18F-FDG PET has been successfully applied in clinical practice to detect a wide variety of tumor types, including lymphoma, lung, colon and bile duct cancer. In the present study, a case of bile duct adenoma with low-grade atypia was reported, revealing the uptake of 18F-FDG. 18F-FDG PET may be able to detect premalignant tumors of the bile duct, although whether 18F-FDG PET is able to differentially discriminate between diagnoses of adenoma and carcinoma of the bile duct remains to be fully elucidated, and the assessment of further case studies is required.