ABSTRACT:A large mass from the right forelimb of a five-year-old, male, Maltese dog, was resected surgically and examined histopathologically. Grossly, the 4 × 6 cm mass was well-demarcated and firm. Microscopically, the mass was characterised by neoplastic mononuclear cells with large round hyperchromatic nuclei and scant cytoplasm. The neoplastic tumour cells were separated by thick or thin collagen septa and were arranged in an alveolar pattern forming cell nests. Immunohistochemical detections of the tumour revealed positive reactions for vimentin, desmin and myogenin, but the tumour was negative for alpha smooth muscle actin (α-SMA), S-100, CD3, CD79a, CD68, cytokeratin 8 (CK8) and cytokeratin 18 (CK18). These results showed that the tumour cells originated from skeletal muscle; therefore, the tumour was diagnosed as an alveolar rhabdomyosarcoma.

ABSTRACT:Here we describe a unique uterine mass in a dog with granulomatous lesions caused by filarial larvae from the family Onchocercidae. An 8-year-old female Maltese was presented to a local animal hospital with anorexia, depression, and vaginal discharge. A markedly distended uterus was observed on lateral abdominal radiographs, leading to a clinical diagnosis of pyometra or uterine mass of an unknown origin. During surgery, the left uterine horn contained a 5 cm diameter mass adhered to adjacent soft tissue. On gross inspection, the mass contained numerous white nematodes. Microscopically, this mass was characterised by a granulomatous inflammation of the myometrium and endometrium. Because all of the nematodes were dead, definitive species identification was not possible. However, based on the histologic appearance, these nematodes were tentatively identified as Dirofilaria immitis larvae.