UK DIAGNOSTIC ROUNDS (CONT.)
spaces and vessels in the cerebrum, cerebellum, and spleen. Small, medium and large caliber vessels in multiple organs had variable degrees of intimal, subintimal and myointimal mineralization. Histopathologic lesions were not present in the brainstem, pancreas, rumen, reticulum, omasum, abomasum or intestinal tract.
Te gross, histopathologic, and clinicopathologic findings in this ewe were consistent with metastatic carcinoma, although the exact origin of the neoplastic cells could not be definitively determined. Primary hepatobiliary neoplasia documented in sheep include hepatocellular adenoma (benign), hepatocellular car- cinoma, hepatoblastoma, biliary adenoma (rare), and cholangiocarcinoma. Of note, cholangiocarcinomas are highly invasive and are known to metastasize frequently in all species affected. Te most frequent sites include lymph nodes, lungs, peritoneal cavity, and abdominal serosa. Metastasis is common in sheep and tumors may be disseminated throughout the body and virtually any organ can be affected. Interestingly, infection with liver flukes is strongly linked to biliary carcinoma in humans. Regardless, chronic inflamma- tion within the bile duct is thought to facilitate tumor development. Differentiation of primary hepatobi- liary tumors from adenocarcino- mas that metastasize to the liver is difficult when the primary site of origin cannot be determined, although no larger masses were identified elsewhere in this ewe. Immunohistochemical stains to specifically identify the neoplastic cell origin were not readily avail- able. Based on clinicopathologic results from fecal examination, endoparasitism was mild and considered an incidental finding.
In summary, this report describes an uncommon case of metastatic carcinoma in a 3-year-old ewe.
32 KVMA News - Diagnostic Rounds
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