Cutaneous angioleiomyoma in a black-tailed prairie dog (Cynomys iudovicianus).

A 3-year-old male black-tailed prairie dog (Cynomys iudovicianus) was presented with a dome-shaped cutaneous mass over the left femur. Microscopically, the mass was encapsulated and composed of proliferating spindle cells arranged in haphazard, interlacing bundles. There were vascular structures within the mass and some spindle cells had transitioned from the peripheral regions of the vascular wall. Immunohistochemically, the cells expressed vimentin, α-smooth muscle actin, desmin and heavy caldesmon. Based on these findings, the mass was diagnosed as a cutaneous angioleiomyoma. To the best of our knowledge, this is the first case of cutaneous angioleiomyoma in a black-tailed prairie dog.