Incomplete Annular Pancreas with Ectopic Opening of the Pancreatic and Bile Ducts into the Pyloric Ring: First Report of a Rare Anomaly

The patient was a 56-year-old woman who had experienced epigastralgia and dorsal pain several times over the last 20 years. She was admitted for a diagnosis of acute cholecystitis, and severe intra- and extrahepatic bile duct dilatation with inner air density was noted. No papilla of Vater was present in the descending duodenum, and 2 small holes were present in the pyloric ring. Bile excretion from one of the small holes was observed under forward-viewing endoscope. It was considered that the pancreatic and bile ducts separately opened into the pyloric ring. Based on these findings, malformation of the pancreaticobiliary duct was diagnosed. She did not wish treatment, but the obstruction associated with duodenal stenosis was noted after 2 years. Pancreatoduodenectomy was performed as curative treatment for duodenal stenosis and retrograde biliary infection through the bile duct opening in the pyloric ring. The ventral pancreas encompassed almost the entire circumference of the pyloric ring, suggesting a subtype of annular pancreas. Generally, lesions are present in the descending part of the duodenum in an annular pancreas, and the pancreatic and bile ducts join in the papillary region. However, in this patient, (1) the pancreas encompassed the pyloric ring, (2) the pancreatic and bile ducts opened separately, and (3) the openings of the pancreatic and bile ducts were present in the pyloric ring. The pancreas and biliary tract develop through a complex process, which may cause various types of malformation of the pancreaticobiliary system, but no similar case report was found on a literature search. This case was very rare and could not be classified in any type of congenital anomaly of the pancreas. We would classify it as a subtype of annular pancreas with separate ectopic opening of the pancreatic and bile ducts into the pyloric ring.