Pancreaticobiliary maljunction and congenital biliary dilatation.

Pancreaticobiliary maljunction is a congenital malformation in which the pancreatic and bile ducts join outside the duodenal wall, usually forming a long common channel. Because the action of the sphincter of Oddi does not regulate the function of the pancreaticobiliary junction in patients with pancreaticobiliary maljunction, two-way regurgitation occurs. Reflux of pancreatic juice into the biliary tract is associated with a high incidence of biliary cancer. Biliary carcinogenesis in patients with pancreaticobiliary maljunction is thought to follow the hyperplasia, dysplasia, then carcinoma sequence due to chronic inflammation caused by pancreatobiliary reflux. Pancreaticobiliary maljunction is diagnosed when an abnormally long common channel is evident on imaging studies. Congenital biliary dilatation involves both local dilatation of the extrahepatic bile duct, including the common bile duct, and pancreaticobiliary maljunction. Extrahepatic bile duct resection is the standard surgery for congenital biliary dilatation. However, complete excision of the intrapancreatic bile duct and removal of stenoses of the hepatic ducts are necessary to prevent serious complications after surgery.