Expression pattern of c-erbB2 oncoprotein in canine mammary tumours

The aim of present study was to investigate the c-erbB2 expression pattern in various histological types of canine mammary tumours. A total of 74 grossly suspected mammary tumours were collected from different veterinary hospitals in 10% buffered formalin, of which 65 were confirmed as tumours on histopathological examination. Among them, 11 (16.92%) were benign and 54 (83.08%) were malignant tumours. Representative tissue sections from each case were subjected to immunohistochemistry employing monoclonal antibody to demonstrate the c-erbB2 oncoprotein expression. The immunolabelling for c-erbB2 oncoprotein was observed in the cell membrane and cytoplasm of neoplastic cells. On immunohistochemical studies, 23/54 (42.59%) of malignant tumours showed c-erbB2 oncoprotein overexpression. Different histological types that were found positive for c-erbB2 included papillary adenocarcinoma, malignant mixed mammary tumour, solid carcinoma, squamous cell carcinoma, infiltrative adenocarcinoma, mucinous carcinoma, intraductal carcinoma in situ and malignant myoepithelioma. Mammary tumours of connective tissue origin (6 cases) were conspicuously immuno-negative. It could be inferred that malignant mammary tumours exhibit frequent overexpression of c-erbB2 oncoprotein than benign ones and among them tumours of epithelial origin are mostly involved.