Alveolar rhabdomyosarcoma in a dog confirmed using myogenin immunohistochemistry: a case report

Abstract

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.

A primary multiple pleomorphic rhabdomyosarcoma of the heart in an adult dog

“…This disease usually occurs in dogs up to 18 months of age which indicates a juvenile predisposition [ 6 – 9 ]. Other locations of RMS, both primary and secondary are heart [ 15 – 17 ], brain [ 18 ], spinal cord [ 19 ], orbit [ 20 , 21 ], ovary [ 5 ], oral cavity including tongue [ 22 ] and maxillary gingiva [ 6 ], esophagus [ 23 ], larynx [ 24 ], and forelimb [ 25 ]. RMS is very aggressive with distant metastases developing early in the course of disease.…”