A 13-year-old female scimitar-horned oryx (Oryx dammah) died after progressive anorexia, weight loss, and depression. The necropsy showed that the retroperitoneum was compressed by a large white-to-tan uterine mass and on several sections of the mass, the uterine wall was markedly thickened because of ill-defined transmural tumor tissue. Metastatic nodules were detected in the omentum, mesentery, diaphragm, and lung. The genital tract and pulmonary and abdominal nodules exhibited highly pleomorphic sarcoma. The primary and metastatic neoplastic cells showed positive results for vimentin, desmin, and sarcomeric actin, and negative results for smooth muscle actin. Uterine metastatic rhabdomyosarcoma was diagnosed on the basis of the gross, histopathology and immunohistochemistry results.
Keywords: immunohistochemistry; oryx; rhabdomyosarcoma; uterus.