To summarize the diagnosis and treatment experience of extrahepatic bile villous tubular adenoma (EHBVTA) unexpectedly found during operation.

Clinical data of 2 patients with EHBVTA admitted to Department of Hepatobiliary and Pancreatic Surgery of Chinese PLA General Hospital residing in the Seventh Medical Center from April 2021 to April 2022 were retrospectively analyzed. The case 1 was male, aged 66 years, and the case 2 was female, aged 59 years. Clinical symptoms were intermittent epigastric pain, and no evident abnormality was found by laboratory testing. Preoperative imaging examination of case 1 showed gallbladder stones, common bile duct stones, dilatation of intra- and extra-hepatic bile ducts complicated with wall thickening. Preoperative imaging examination of case 2 detected low bile duct obstruction and circular filling defect at the lower end of common bile duct, which were considered as common bile duct stones and gallbladder stones.

In case 1, laparoscopic cholecystectomy and choledocholithotomy were performed, and "bile duct adenoma (middle and upper segments)" was found intraoperatively. Extrahepatic bile duct resection and cholangioenterostomy were performed during the first stage. Case 2 underwent laparoscopic cholecystectomy and bile duct exploration, and "bile duct adenoma (lower segment)" was observed during the operation. T tube was placed for drainage, and pancreaticoduodenectomy was repeatedly performed after 4 weeks. Postoperatively, both two patients were pathologically diagnosed with "EHBVTA". Case 1 developed high-grade intraepithelial tumor with canceration. No recurrence was observed in two patients upon the date of manuscript submission.

The incidence of EHBVTA is low, and preoperative diagnosis is challenging. Enhancing the diagnostic rate and radical resection play a critical role in obtaining favorable prognosis.