Carcinossarcoma mamário em uma gata: caracterização anatomopatológica e imuno-histoquímica

Abstract

Background: Mammary tumor is uncommon in cats. In felines is most frequently observed in old animals and Siamese breed. Apparently there is no relation between the age of the animal at the time of spay how is observed in dogs, although the progression from a focal hyperplasia to an adenoma or a carcinoma is known. The ratio between malignant and benign tumors is estimated between 9:1 and 4:1, most of them are adenocarcinomas and highly metastatic behavior. Mammary carcinosarcoma is rare in felines. The objective of this work was to describe a case of carcinosarcoma in a female cat. Case: Mammary gland mass from a 13-year-old, intact female Siamese cat was submitted for biopsy. The tumor was observed recently by the owners, who reported that the animal never received contraceptives. Macroscopically, it was observed focally extensive poorly demarcated, whitened, fi rm mass measuring 4.0 x 3.0 x 1.5 cm, recovered by skin with central round area of ulceration measuring 2.0 cm in diameter. Histologically, the neoplasm was composed of epithelial cells and spindle mesenquimal cells with bone and cartilaginous differentiation. Immunohistochemistry for cytokeratin AE1/AE3 and 8/18 were stained intracitoplasmatic positive, accentuated (+++) and moderate (++), respectively in tubular epithelia in more than 50% of the cells. There was immunostaining for vimentin in the cytoplasm of mesenchymal neoplastic cells, cartilaginous and tubular epithelial cells with moderate intensity (++) in less than 50% of the cells. Discussion: Carcinosarcoma is a rare neoplasm in cats and have being reported in the mammary gland and in the lungs. The neoplasm is characterized by mesenchymal and epithelial cells. In many cases the histological exam is insuffi cient to determinate the diagnosis, being necessary to do the immunohistochemistry (IHC) exam to verify vimentin and cytokeratin coexpression in neoplasic cells. Histologically, was observed epithelial and mesenchymal characteristics, confi rmed by IHC. In another paper, carcinosarcoma demonstrated similar arranged, as heterogenic cellular composition and infi ltrative proliferation of mesenchymal cells. In this case report was also observed cartilaginous and osseous differentiation. Some carcinosarcoma can present differentiated mesenchymal tissue and a mixture of all carcinomatosos and sarcomatosos elements in the same neoplasic mass. Histogenesis of carcinosarcoma remains uncertain thus far, although two theories suggest its origin: a multiclonal and other monoclonal. The fi rst one suggests that mesenchymal and epithelial cells are originated from two or more different base cells. The second theory suggests that the tumors behavior is the result of a totipotent ability of neoplasic cells to differ and be histologically recognizable as epithelial and mesenchymal structures. In this study, tubular epithelial cells were positive stained for cytokeratins (AE1/AE3 and 8/18) and to vimentin, which suggest a monoclonal origin, because it was observed epithelial and mesenchymal differentiation. According to localization, morphology features and immunohistochemistry evaluation, the present study reports a rare case of carcinosarcoma in a cat.