34 year old male patient came with recurrent pancreatits. Barium meal showing smooth narrowing in the second part of duodenum. Annular pancreas was confirmed on MRCP.
Annular pancreas is a rare congenital anomaly in which incomplete rotation of the ventral anlage leads to a segment of the pancreas encircling the second part of the duodenum. It has a prevalence of one in 2,000 persons and occurs either as an isolated finding or with other congenital abnormalities. There are two types of annular pancreas: the extramural type and the intramural type. In the extramural type, the ventral pancreatic duct encircles the duodenum to join the MPD. In the intramural type, the pancreatic tissue is intermingled with muscle fibers in the duodenal wall, and small ducts drain directly into the duodenum.
Annular pancreas can be diagnosed on the basis of CT and MR imaging findings that reveal pancreatic tissue and an annular duct encircling the descending duodenum. ERCP is useful in substantiating the diagnosis and defming the ductal anatomy. ERCP shows a normally located main duct in the pancreatic body and tail and encirclement of the duodenum by a small duct in the pancreatic head. In most cases (85%), the duct within the annular portion of the pancreas communicates with the main pancreatic duct.