Primary gastric histiocytic sarcoma in a dog--a case report.

A 12-year-old intact female mixed breed dog was presented for chronic, intermittent vomiting and diarrhoea. On endoscopic examination a protruding mass arising from the mucosal surface of the pyloric region was detected. Cytological and histological examination revealed an accumulation of pleomorphic round/oval phagocytic cells suggesting histiocytic origin. This was confirmed by immunohistochemistry. No extra-gastric involvement was detected on clinical examination or at necropsy. This is the first report of primary gastric histiocytic sarcoma in a dog.