Unusual immunophenotype of a soft tissue sarcoma in a European polecat (Mustela putorius)

The most commonly reported tumors in ferrets are carcinomas, followed by ro und cell tumors. Soft tissue sarcomas are reported and characterized much l ess frequently. Because domesticated ferrets (Mustela putorius furo) are di rect descendants of European polecats (Mustela putorius), the types and pre valence of tumors are expected to be similar in the two species. Presented here is a case report of unusual immunohistochemical staining characteristi cs of an abdominal wall leiomyosarcoma in a close relative of domestic ferr ets, the European polecat. Sections of tissue were preserved in 10% buffere d formalin, embedded in paraffin, and sectioned at 5 mum. Routine staining with hematoxylin and eosin and several immunohistochemical tests were per f ormed to identify the tumor tissue of origin., Although the tumor did not s tain with antibody to desmin, further staining for smooth muscle actin was consistent with a smooth muscle origin. To the authors' knowledge, this rep ort is the first description of a leiomyosarcoma in the European polecat. T his report emphasizes the importance of using additional secondary markers to accurately diagnose anaplastic tumors.