[A case of intrahepatic cholangiocarcinoma associated with Type IV choledochal cyst].

Anomalous union of the pancreaticobiliary duct (AUPBD) is a congenital anomaly that is defined as a junction of the bile duct and pancreatic duct outside the duodenal wall. This anomaly results in a loss of normal sphincteric mechanisms at the pancreaticobiliary junction. As a result, regurgitation of pancreatic juice into the biliary system develops and causes choledochal cysts, choledocholithiasis, cholangitis, pancreatitis and malignancy of the biliary tract. Gallbladder cancer or common bile duct cancer associated with AUPBD and choledochal cysts have been frequently reported. But, intrahepatic cholangiocarcinoma associated with this condition has been only rarely reported. Here, we report a case of intrahepatic cholangiocarcinoma associated with AUPBD and choledochal cyst.