IMMUNOHISTOCHEMICAL LOCALIZATION OF CYTOKERATIN AND VIMENTIN INTERMEDIATE FILAMENT PROTEINS IN CANINE MAMMARY-TUMORS

Monoclonal antibodies to human stratifying keratin (StK), simple kerat in (SK), broad spectrum keratin (BSK) and vimentin mere applied to 47 canine mammary tumours (three benign hyperplasia, 26 benign mammary tu mours, one malignant mixed tumour, two malignant complex tumours, seve n lobular carcinomas, three papillary carcinomas and five squamous cel l carcinomas). In benign hyperplasia the SK antibody reacted with acin ar and duct epithelial cells; the StK and BSK antibodies reacted stron gly with duct epithelial cells and myoepithelium. Neoplastic epithelia l cells in the canine mammary tumours expressed mainly keratins of str atified epithelia rather than those of simple epithelia. Myoepithelial cells in complex and mixed tumours can express StK and vimentin. The finding might be helpful in the assessment of complex tumours where st romal reactions may be confused with myoepithelial neoplastic prolifer ation. Stromal mesenchymal tissues, including precartilage in complex tumours, and clearly differentiated myoepithelial cells always stained positively for vimentin. Occasional carcinoma cells stained positivel y for vimentin.