An unusual variant of type I common bile duct duplication associated with ampullary carcinoma.

Common bile duct duplications represent exceptionally rare congenital anomalies of the biliary tract. In this case report we document an unusual variant of common bile duct duplication in a 79-year-old man who underwent a pancreaticoduodenectomy for ampullary cancer. The duplication consisted of two unseparated, completely-layered, common bile ducts which originated above the cystic duct junction and terminated prior to the point of insertion into the pancreas, where the two lumens converged into a single duct. Duplication of the bile duct is rare and often goes undetected. In the present case, the anomaly was found incidentally in a patient who had a pancreaticoduodenectomy for an ampullary carcinoma. However, duplication may be associated with choledocholithiasis, cholangitis, pancreatitis, and pancreaticobiliary malignancies and it is important to be aware of the condition.