Double common bile duct: a case report and a review of the Japanese literature.

Background: A double common bile duct (DCBD) is a rare congenital anomaly. We report the case of a 60-year-old Japanese female, whose common bile duct divided into 2 channels and both channels opened individually into the second portion of the duodenum. This is the fourth reported case of DCBD with a choledochal cyst and pancreaticobiliary maljunction (PBM).