Tubulopapillary carcinoma of the mammary gland in a maned wolf (Chrysocyon brachyurus): histopathological and immunophenotypical analysis

A maned female wolf (Chrysocyon brachyurus) showed nodules in the inguinal and left abdominal cranial mammary glands. The mammary gland was surgically excised, and microscopic analysis revealed epithelial cell proliferation in a tubular and papillary pattern; delicate fibrovascular stalks presenting numerous layers of moderately pleomorfic epithelial cells were observed. This histologic appearance was compatible with a diagnosis of mammary tubulopapillary carcinoma. The immunohistochemical profile revealed nuclear positivity for estrogen (70%) and progesterone (at least 90% of the neoplastic cells). The myoepithelium-associated with neoplastic cells lacked integrity, as evidenced by failed smooth muscle alpha actin reactivity in microinvasive areas. A low proliferation index was observed (3.4%). To the authors' knowledge, the present case represents the first finding of female tubulopapillary carcinoma in a mammary gland in this species