Association of extrahepatic bile duct duplication with pancreaticobiliary maljunction and congenital biliary dilatation in children: a case report and literature review.

We herein report a case of cystic-type congenital biliary dilatation (CBD) in whom an extremely rare anomalous duplication of the common bile duct and pancreaticobiliary maljunction were diagnosed intraoperatively by meticulous surgical manipulations via conventional open surgery. By performing a dissection at the outer epicholedochal layer of the cyst, a thin cord-like structure shown to be the distal part of the common bile duct was identified. A further exploration revealed that the most distal (extra- and intrapancreatic) part of the common bile duct was duplicated, and each branch of the duct was connected to the main and accessory pancreatic ducts. The experience with our case and a literature review showed that extrahepatic bile duct duplication is generally associated with pancreaticobiliary maljunction and CBD. We conclude that an extremely careful exploration with delicate and meticulous surgical manipulation is essential to identify these morphological anomalies and prevent intraoperative and postoperative complications of CBD, such as pancreatic duct injury or pancreatitis.