Rhabdoid tumor in the gluteal region of a Shit-tzu dog

Rhabdoid tumor is an aggressive neoplasm of animals and human. It is similar with rhabdomyosarcoma histopathologically. But cellular origin of this neoplasm showed no striated muscle origin by immunohistological and ultrastructural studies. Castrated male Shit-tzu dog, 6 years old, had a mass in the left gluteal region near to the tail. The mass was examined histopathologically and immunohistologically. Histopathologically, the tumor was consisted of large polygonal cell with abundant eosinophilic cytoplasm. The nuclei in some cells were marked eccentrically located. Immunohistochemically, many neoplastic cells were positive for vimentin. These findings were similar to histopathological and immunohistological features of human rhabdoid tumor and few rhabdoid tumors in animals.