Anomalous intrahepatic portal system in a patient with hilar bile duct cancer

We report a case of anomaly of the intrahepatic portal system in a 65-year-old man with hilar bile duct cancer. Preoperatively, percutaneous transhepatic portography demonstrated that there was a right posterior portal vein arising from the main portal vein. In addition, a large portal branch originated from the left portal vein and coursed toward the right hepatic lobe. Following portal embolization of the right posterior branch, the patient underwent an extended right hepatectomy with a caudate lobectomy. Intraoperatively, to the left at the porta hepatis and then it first gave off the right anterior portal vein originated from the left portal vein and coursed toward the right hepatic lobe horizontally behind the gallbladder and then separated into superior and inferior segmental branches to supply the right anterior segment of the liver. The ramification of some major branches without malposition of the gallbladder or round ligament was the important clinical feature of this anomaly.