Hepatectomy for cholangiocarcinoma complicated with right umbilical portion: anomalous configuration of the intrahepatic biliary tree.

The right umbilical portion (right-sided round ligament) has been discussed as an intrahepatic portal venous anomaly associated with "left-sided gallbladder" in several reports. We treated two patients with right umbilical portion (RUP) associated with cholangiocarcinoma. Left hepatectomies were performed, preserving the residual hepatic blood flow and biliary continuity. From our experience in these patients we propose the presence of anomalous configuration of the intrahepatic biliary tree in RUP, because both patients showed medial segmental bile ducts ramified from the right and left hepatic ducts. In general, although the medial segmental bile duct ramified from the left, we surmised that this abnormal bilateral drainage pattern may not be a rare phenomenon in RUP. Special attention may be required to focus on the anatomy of the portal tributaries and biliary ramifications in RUP.