Intraductal Papillary Neoplasm of the Bile Duct Occurring 37 Years after Surgery for Congenital Biliary Dilatation

We present the case of a 54-year-old woman who was diagnosed with intraductal papillary neoplasm of the bile duct (IPNB) in the remnant intrapancreatic bile duct, 37 years after surgery for congenital biliary dilatation. Endoscopic ultrasonography revealed a papillary, low-echoic mass in the intrapancreatic bile duct, and peroral cholangioscopy revealed a papillary mucosa. A pancreaticoduodenectomy was performed, and the patient was pathologically diagnosed with type 1 pancreatobiliary-type IPNB with associated invasive carcinoma. As a similar atypical epithelium was identified in the pancreatic duct, it was suggested that the IPNB extended longitudinally to the pancreatic duct through the common channel.