Malignant Myoepithelioma with a Squamous Epithelial Component in the Mammary Gland of a Cynomolgus Monkey

Abstract

A solid mass arising from the mammary gland was found in a 7-year-old female cynomolgus monkey. Histologically, the mass consisted of 2 components: spindle-shaped or ovoid sarcomatous cells and squamous epithelial cells. Metastatic nodules noted in the lung, liver and the gallbladder had the same histological features as the mammary mass. Immunohistochemistry revealed that the sarcomatous cells were positive for alpha-smooth muscle actin (alpha-SMA), vimentin, calponin, S-100 protein, epithelial membranous antigen (EMA), cytokeratin (large spectrum) and cytokeratin 14 (CK 14) in the cytoplasm, and p53, erbB-2 and progesterone receptor in the nuclei, but negative for desmin and estrogen receptor. The squamous epithelial cells were positive for EMA, cytokeratin (large spectrum) and CK 14, but negative for the rest. Both sarcomatous and squamous epithelial components were negative for glial fibrillary acidic protein (GFAP). Based on histological and immunohistochemical features, the present case was diagnosed as a malignant myoepithelioma with a squamous epithelial component in the mammary gland with distant metastases.

Neoplasia and Proliferative Disorders of Nonhuman Primates

“…There is also a report of mammary adenocarcinoma in a male squirrel monkey (Waggie et al, 2000) and gynecomastia and galactorrhea has been described in a male rhesus macaque with disseminated carcinoma of unknown origin (Ringler and Abrams, 1972). Mammary carcinoma has also been described in a mandrill (Choi et al, 2001) and there is a report of a myoepithelioma arising in the mammary gland of a cynomolgus macaque (Yang et al, 2003). Reports of mammary tumors are lacking in New World primates; however whether this is a true reflection of low incidence is not known.…”

Spontaneous lesions in the reproductive tract and mammary gland of female non‐human primates

“…A malignant myoepithelioma has been reported in a cynomolgus (Yang et al, 2003). The tumor consisted of pleomorphic spindle cells arranged in sheets between fibrous connective tissue trabeculae.…”