Morphological and immunohistochemical assays of surgically removed mammary gland tumors in bitches

Abstract

In this study an estimation of the malignancy of mammary gland tumors was carried out based upon clinical examination, macroscopic and pathohistological characteristics of neoplasms and expression of cytokeratins. In the study 60 bitches of different ages, race and reproductive status with clinically evident signs of mammary gland tumor were included. After clinical examination the mammary gland tumors were excided, after which tissue samples were taken for subsequent pathohistological and immunohistochemical analysis. Tumors are classified according to the latest WHO recommendation (1999). The ratio of malignant tumors vs. non-malignant was 1.9 : 1. The most frequent malignant tumor was adenocarcinoma (n=17), followed by complex adenocarcinoma (n=12), carcinoma in mixed tumors (n=5), mucinous carcinoma (n=3), and fibrosarcoma and osteosarcoma, one of each. Most common benign changes were benign mixed tumors (n=10) and adenoma (n=6). Hyperplasia of the mammary gland was found in two bitches, while chronic steatitis, fibrosis and complex adenoma were reported only in individual cases. The expression of cytokeratins on different malignant and benign neoplastic cells was determined by the immunohystochemical peroxidase-antiperoxidase method. In simple carcinoma a positive reaction was established within the epithelium of the lumen of the alveoli and in the stromal tumor cells present in the lymph and blood vessels. In the cells of complex tumors cytokeratin was expressed on epithelial cells as well as on spindle, stellate and myoepithelial cells. .