Scirrhous adenocarcinoma of the rectum in a cow.

Clinical and pathological examinations were performed on a 3-year-old Holstein-Friesian cow with scirrhous adenocarcinoma of the rectum. Hemorrhagic diarrhea causing rectal stenosis was a principal clinical manifestation. Microscopically, cancerous transformation of the intestinal epithelium was observed in the rectal crypts. Irregular glandular arrangements containing PAS positive and eosinophilic mucus were observed in the lumen, which were surrounded by scirrhous collagenous fibers. The neoplastic epithelial cell had round or ovoid nucleus and slightly eosinophilic cytoplasm. Metastatic lesions were localized in the marginal and medullary sinuses of the anorectal lymph nodes.