Characterization of metastatic intestinal adenocarcinoma with differentiation into multiple morphologic cell types in a virginia opossum

A captively maintained mature male opossum (Didelphis virginiana) utilized in a research protocol was presented with clinical signs of chronic diarrhe a and severe muscle wasting. At necropsy, there was multifocal mural gastri c, intestinal, and urinary bladder thickening, concurrent bilateral hydrour eter and hydronephrosis, and extensive fibrous abdominal adhesions. Histolo gic evaluation revealed intestinal adenocarcinoma with coelomic metastasis to the stomach and urinary bladder. The adenocarcinoma was evaluated using histochemistry and electron microscopy. Paneth, enteroendocrine, and goblet cell differentiation was documented in primary and metastatic sites. This unique presentation of intestinal adenocarcinoma has not previously been re ported in the opossum or any other animals. Intestinal neoplasia with Panet h cell differentiation is extremely rare and has been reported in humans wi th familial adenomatous polyposis.