Co-expression of vimentin and cytokeratin in bitch mammary gland tumors

This work presents the results of immunohistochemical studies on the distribution of intermediary filamentous proteins vimentin and cytokeratin in bitch mammary gland tumors, which had been previously classified according to the latest WHO-classification (1999). The overall test specimen included 45 bitches of different breeds and age, which resulted in diagnosing 27 malignant neoplasms, 11 benign neoplasms, and 3 hyperplastic-dysplastic changes, while 4 test specimens were taken from healthy bitches. The commonest malignant neoplasms were: simple adenocarcinoma (13 cases) and complex adenocarcinoma (7). Among the benign neoplasms the ones that dominated were benign mixed tumors (8 cases). Vimentin was expressed on neoplastic proliferative suprabasal myoepithelial cells of simple adenocarcinomas; on resting, spindleshaped and star-shaped myoepithelial cells of complex adenocarcinomas; on cartilage cells of carcinomas in the mixed tumor and benign mixed tumors; on osteoid cells of osteosarcoma; and on myofibroblasts of simple adenocarcinomas, complex adenocarcinomas, carcinomas in the mixed tumor and benign mixed tumors, and connective tissue fibres of fibrosarcoma. The expression of cytokeratin was noticed on canalicular and alveolar lumen epithelium of simple adenocarcinomas; on epithelial cells of complex adenocarcinomas, carcinomas in the mixed tumor, mutinous carcinomas, fibrosarcoma and of osteosarcoma; on resting and starshaped myoepithelial cells of complex adenocarcinomas and carcinomas in the mixed tumor; as well as on spindle-shaped myoepithelial cells of carcinomas in the mixed tumor. Proliferative suprabasal myoepithelial cells of simple adenocarcinomas showed the co-expression of vimentin and cytokeratin, and so did the resting and spindle-shaped myoepithelial cells of complex tubular adenocarcinomas, whereas in complex solid adenocarcinomas the coexpression was also shown on star-shaped myoepithelial cells. The coexpression of vimentin and cytokeratin was found on resting myoepithelial cells of benign mixed tumors, simple and complex adenomas, and mammary gland hyperplasia; on spindle-shaped myoepithelial cells of benign mixed tumors, complex adenomas and myoepithelial solid adenomas; and on star-shaped myoepithelial cells of benign mixed tumors.