Gastric duplication: proventricular cystic choristoma on the spleen of a broiler chicken.

Gastric duplication (choristoma) is a very rare anomaly in both humans and other animal species. We report herein a case of proventricular cystic choristoma in a 62-day-old broiler chicken. The broiler chicken was brought from the slaughterhouse to our laboratory after a pale-brown cystic structure closely attached to a thin, compressed spleen was identified. On necropsy, the cystic structure showed a clear mucinous fluid. Histopathologically, the cystic structure was lined by proventricular mucosa presenting in folds and sulci. Submucosal proventricular glands, consisting of secretory units and collecting tubules, occupied parts of the choristomal wall. The gastric mucosa lining the choristomal wall stained positive with periodic acid-Schiff stain, stained negative with Alcian blue staining, and showed a thin layer of smooth muscle fibers and a thick connective tissue layer with Masson trichrome. Ectopic pancreas was noticed attached to the wall of the choristoma. To the best of our knowledge, this represents the first report of choristoma in an avian species.