Endoscopic diagnosis of pancreaticobiliary maljunction.

Pancreaticobiliary maljunction (PBM) is a congenital anomaly defined as a junction of the pancreatic and bile ducts located outside the duodenal wall, usually forming a markedly long common channel. As the action of the sphincter of Oddi does not functionally affect the junction in PBM patients, continuous pancreatobiliary reflux occurs, resulting in a high incidence of biliary cancer. PBM can be divided into PBM with biliary dilatation (congenital choledochal cyst) and PBM without biliary dilatation (maximal diameter of the bile duct ≤ 10 mm). The treatment of choice for PBM is prophylactic surgery before malignant changes can take place. Endoscopic retrograde cholangiopancreatography (ERCP) is the most effective examination method for close observation of the pattern of the junction site. When the communication between the pancreatic and bile ducts is maintained, despite contraction of the sphincter on ERCP, PBM is diagnosed. In these patients, levels of pancreatic enzymes in the bile are generally elevated, due to continuous pancreatobiliary reflux via a long common channel. Magnetic resonance cholangiopancreatography and 3D-computed tomography can diagnose PBM, based on findings of an anomalous union between the common bile duct and the pancreatic duct, in addition to a long common channel. Endoscopic ultrasonography and intraductal ultrasonography can demonstrate the junction outside the duodenal wall, and are useful for the diagnosis of associated biliary cancer. Gallbladder wall thickness on ultrasonography can be a screening test for PBM.