Vulvar lipoleiomyoma in a dog.

A vulvar neoplasm from a 5-year-old female Siberian Husky dog was removed surgically and examined histologically. Macroscopically, the neoplasm was firm, white, and measured 6 x 4 x 3 cm. Microscopically, the neoplasm was expansile, nonencapsulated, and composed of lobules of mature adipocytes ad-mixed with streams and bundles of well-differentiated smooth muscle cells. Immunohistochemically, the neoplastic cells had strong diffuse cytoplasmic immunoreactivity for alpha-smooth muscle actin and desmin, and no immunoreactivity for cytokeratin or vimentin. On the basis of gross, histopathologic, and immunohistochemical findings, a diagnosis of lipoleiomyoma was made. This is, to the author's knowledge, the first report of canine vulvar lipoleiomyoma.