Co-existence of intestinal adenocarcinoma and leiomyosarcoma in a Schnauzer dog

A 7-year-old castrated male Schnauzer was presented with melena and inappetence. Laboratory examination revealed mild anemia. Abdominal ultrasonography showed abnormal enlargement of intestinal segment and a oval mass with soft tissue density. After surgical resection of the enlarged intestine including the mass, histopathologic examination showed that the mass was tentatively diagnosed as synchronous occurrence of gland cell-and mesenchymal cell-origin tumors. Subsequently, immunohistochemistry showed positivity to cytokeratin AE1/AE3 in the gland cells and positivity to α-smooth muscle-specific actin, but negative expression of c-Kit, suggesting the co-existence of adenocarcinoma and leiomyosarcoma. Follow-up examination after 3-year of the surgery confirmed that the dog remained healthy and did not show recurrence of the tumors.