Pathological and immunohistochemical studies in mammary gland tumours affecting male dogs

The study was conducted on 40 clinical cases suspected of canine mammary tumours collected over a period of 2 years. Out of total 38 cases diagnosed as CMT, two (5.26%) cases were noticed in male Labrador dogs of 2.5 and 7 yrs age which were observed in the caudal abdominal and cranial thoracic pair of glands, respectively. The male dog exhibited generalized clinical signs with variability in size. Serum estrogen and progesterone levels in both dogs were higher than the basal normal values. High levels of heavy metals concentration viz. iron, zinc, mercury and cadmium were noticed in the mammary tissues and serum samples of tumour affected dogs. Grossly, growth was hard, firm lobulated pattern with ulceration in one case and soft diffuse round appearance in another case. Tumours were classified as carcinosarcoma and lipoma, respectively. Carcinosarcoma was classified as complex adenocarcinoma forming papillary growths with chondrosarcoma and myxomsarcoma components. Lipoma revealed adipocytes arranged in variable sized lobules separated by connective tissue septa. Immunohistochemical expression of p53 and estrogen receptor alpha (ERα) gene was found to be negative in both cases. Epithelial component (complex carcinoma) in carcinosarcoma showed intense positive immunoreactivity for pancytokeratin in luminal epithelial cells and moderate cytokeratin-14 expression in proliferated myoepithelial cells forming papillary growth.