Pancreaticobiliary Maljunction and Congenital Biliary Dilatation

Congenital biliary dilatation (CBD) is a congenital malformation involving both local dilatation of the extrahepatic bile duct, including the common bile duct, and pancreaticobiliary maljunction (PBM) that is thought to develop as a misarrangement of the embryonic connections in the pancreaticobiliary ductal system. Patients can be diagnosed with CBD at any age, but more than two-thirds of cases are diagnosed in children younger than 10 years of age. The major clinical symptoms are recurrent abdominal pain, nausea and vomiting, and mild jaundice. The occurrence of signs and symptoms is explained by the bile and pancreatic flow being disturbed by protein plugs. In PBM, the sphincters of the pancreatic duct and the bile duct cannot work, and this long common channel permits reflux of pancreatic juice freely into the biliary tract. This free reflux may be a key factor in the pathogenesis of malignant changes in the bile duct. According to a nationwide survey performed in Japan, cancer of the biliary tract was found in 21.6% of 997 patients with CBD/PBM diagnosed in adulthood and was developed biliary tract cancer 15–20 years earlier than individuals without PBM. Immediate extrahepatic bile duct resection is recommended once a definitive diagnosis is established because juvenile patients with CBD can develop cholangitis and/or cancer even if asymptomatic. However, reports of intrahepatic stones and/or bile duct carcinoma after surgery are gradually increasing. Therefore, careful long-term follow-up is very important.