Fibromuscular annular pancreas. A variant of pancreatic malformation?

All reported cases of annular pancreas consist of histologically normal pancreatic tissue. The most widely accepted theory of the pathogenesis of the pancreatic annulus agrees with, and is partially based on this fact. The pancreatic annulus encircling the stenotic second part of the duodenum in our patient was composed of fibromuscular tissue with lymph glands and a few pancreatic acini scattered among the smooth muscle fibers. This unique histologic variant of annular pancreas possible arose from a double fault in the ventrial anlage of the embryonal pancreas: faulty rotation (giving rise to the annular malformation) and abnormal histologic structure.