A simple ductal mammary papilloma in a male maned wolf (Chrysocyon brachyurus)

A 1-cm-diameter nodule was identified in the left inguinal mammary gland of a 9-year-old male maned wolf (Chrysocyon brachyurus). The mass was surgically excised and examined histologically. Microscopically, the neoplasm consisted of papillary proliferations of epithelial cells on well-defined fibrovascular stalks. A myoepithelial layer was located between the single layer of epithelial cells and the fibrovascular stalk. This histologic appearance was compatible with a diagnosis of simple ductal mammary papilloma. Immunohistochemical staining was positive for p63, cytokeratins AE1/AE3, and estrogen receptors. The clinical and histologic observations in the present case indicate that male maned wolves may develop mammary tumors that are similar to those observed in domestic dogs and humans.