Imaging description

Pancreaticobiliary maljunction (also known as anomalous pancreaticobiliary ductal union or common channel syndrome) is a congenital anomaly in which the pancreatic and biliary ducts join prematurely outside the duodenal wall, so that two-way reflux can occur between the pancreatic and biliary systems [1]. The diagnosis can be made at ERCP or MRI when a long common channel is seen between the distal pancreatic and biliary ducts (Figures 26.1–26.4). Threshold lengths of 12 to 15 mm have been suggested to make the diagnosis [1,2], although in my experience the diagnosis can generally be made on visual inspection alone. Because hydrostatic pressures are usually higher in the pancreatic duct, pancreaticobiliary maljunction often results in reflux of pancreatic secretions into the bile duct, and so can be diagnosed biochemically when high levels of amylase are found in bile obtained from the bile duct or gallbladder, either percutaneously or at laparotomy [1]. Visualization of pancreaticobiliary reflux in common channel syndrome has also been reported using secretin-stimulated dynamic MRCP [3].

Importance

Pancreaticobiliary maljunction has been linked with a wide variety of pancreatic and biliary diseases, including gallbladder cancer, cholangiocarcinoma, pancreatic cancer, adenomyomatosis, pancreatitis, and cholelithiasis [4]. It should be noted that these associations have been extensively described in reports from Japanese and Taiwanese investigators, with far fewer reports from Europe and the United States. As such, the global relevance of pancreaticobiliary maljunction is unclear, although conceptually it is possible that mixing of pancreatic and biliary secretions might be pathogenic or even carcinogenic.