Adenocarcinoma of the distal esophagus and esophageal-proventricular junction in a yellow-naped parrot.

A 57-y-old male yellow-naped parrot (Amazona auropalliata) was presented because of lethargy, inappetence, and weight loss. Hematology and serum biochemistry were unremarkable, and imaging revealed a mass in the distal esophagus at the coelomic inlet. The luminal diameter of the esophagus was reduced in this area, and passage of ingesta was limited. Following gavage feeding, the patient died and was submitted for autopsy. At postmortem examination, the noted mass effect was a thickening of the distal esophagus with adherent, coalescing, soft, pale-tan plaques on the mucosal surface. Additional gross findings included pale-tan, opaque feed material oozing from the dorsum of the lungs and covering the cranial air sacs. Histology of the esophagus, esophageal-proventricular junction, and proximal proventriculus revealed an unencapsulated, infiltrative, transmural neoplasm that extended from the mucosal surface deep into the muscularis, almost to the adventitia. The neoplasm was composed of cuboidal cells arranged in islands and tubules, consistent with an adenocarcinoma, a rarely reported entity in the esophagus of psittacine birds and to our knowledge not reported previously at the esophageal-proventricular junction.