Brunner's Gland Adenocarcinoma in an Aged Western Gorilla (Gorilla gorilla).

A 50-year-old male western gorilla (Gorilla gorilla) presented with severe bradypragia, anorexia and vomiting. Despite continuous administration of antiphlogistic analgesic drugs and supportive care, the animal died and was submitted for post-mortem examination. Macroscopically, a large mass was located in the duodenum. The mucosal surface of the duodenum was irregular and thickened, and the lumen narrowed. The duodenal lesion was identified as a tubular adenocarcinoma and the neoplastic cells were strongly positive for cytokeratin AE1/AE3, cytokeratin 7, cytokeratin 19 and mucin-6 protein. Ultrastructurally, the apical cytoplasm of neoplastic cells had electron dense granules and apical microvilli. This is the first reported case of Brunner's gland adenocarcinoma in a gorilla.