Comparative Study of Pathological Findings for Malignant Pheochromocytoma and Pheochromocytoma in Cattle Detected During Meat Inspection

Abstract

We analyzed the pathological characteristics of one case of malignant pheochromocytoma and five cases of pheochromocytoma in cattle detected at the Kanagawa Prefectural Meat Inspection Station. All cases were elderly Japanese Black and Holstein cattle. In the malignant pheochromocytoma case, tumors were found in the left adrenal gland, the posterior vena cava, and both lungs. In the pheochromocytoma cases, tumors were found in one or both adrenal glands. Microscopically, tumor cells were arranged in alveolar or trabecular pattern separated from each other by a connective tissue stroma with capillaries. The neoplastic cells of the pheochromocytoma were more markedly pleomorphic than those of the malignant pheochromocytoma. Immunostaining showed that neoplastic cells were positive for chromogranin-A and synaptophysin, and the Ki-67 positivity rate was lower in the malignant pheochromocytoma than in the pheochromocytoma. In this study, cases of metastasis without significant pleomorphism or proliferation were identified, suggesting that it is difficult to distinguish between benign and malignant tumors in cattle, similar to tumors in humans.