Clinical significance of the minor duodenal papilla and accessory pancreatic duct.

The accessory pancreatic duct (APD) is the main drainage duct of the dorsal pancreatic bud in the embryo, entering the duodenum at the minor duodenal papilla (MIP). As development progresses, the duct of the dorsal bud undergoes varying degrees of atrophy at the duodenal end. In cases of patent APD, smooth-muscle fiber bundles derived from the duodenal proper muscular tunics surround the APD. The APD shows long and short patterns on pancreatography, and ductal fusion in the two types appears to differ embryologically. Patency of the APD in control cases, as determined by dye-injection endoscopic retrograde pancreatography, was 43%. Patency of the APD may depend on duct caliber, course, and terminal shape of the APD. A patent APD may prevent acute pancreatitis by reducing the pressure in the main pancreatic duct. Pancreas divisum is a common anatomical anomaly in which the ventral and dorsal pancreatic ducts do not unite embryologically. As the majority of exocrine flow is routed through the MIP in individuals with pancreas divisum, interrelationships between poor function of the MIP and increased flow of pancreatic juice caused by alcohol or diet may increase dorsal pancreatic duct pressure and lead to the development of pancreatitis. Wire-guided minor sphincterotomy, followed by dorsal duct stenting, is recommended for acute recurrent pancreatitis associated with pancreas divisum.