Evaluation of Cytokeratin 7 Expression in Different Mammary Gland Neoplasms

BACKGROUND: Cytokeratins are non-contractile intermediate filaments engaged in anchoring and structural functions forming a network to support cytoplasm. Cytokeratin 7 (CK7) expression in human breast carcinomas has proved to be a useful differentiation marker, but its expression in canine mammary gland tumors is poorly understood. OBJECTIVES: Cytokeratin 7 (CK7) expression in human breast carcinomas has proved to be a useful differentiation marker, but its expression in canine mammary gland tumors is poorly understood. METHODS: This research was based on the immunohistochemical study of CK7 in 17 cases of canine mammary gland neoplasms obtained from the Department of Pathology, Faculty of Veterinary Medicine, University of Tehran. Masson’s trichrome staining was performed to differentiate between collagen fibers and smooth muscle. RESULTS: CK7 protein was detected in both epithelial (1 benign mixed tumor, 1 fibroadenoma, 1 complex carcinoma, and 1 carcinoma mixed type) and myoepithelial (1 fibroadenoma, 1 benign mixed tumor, 3 complex carcinomas, 1 ductal carcinoma, and 1 carcinoma mixed type) cells. Fine and thick collagen fibers were observed in the sections stained by Masson’s trichrome. CONCLUSIONS: Despite using CK7 as a differentiation marker in human breast cancer, CK7 had a controversial expression in the epithelial and myoepithelial cells in canine mammary gland neoplasms. Based on the results, CK7 could not be considered as an independent marker for the canine mammary glands epithelial cell detection and a prognostic factor in canine mammary gland neoplasms.