干旱区生态环境知识资源中心

Background: There is in Brazil little information about histopathological features of feline mammary neoplasms. Especially in some Brazilian Northeastern locations such as Rio Grande do Norte (RN), there is complete absence of data regarding feline mammary neoplasm microscopy. Accordingly, this study aimed to describe the histopathology of mammary gland tumors in native domestic cats from the state of RN, Brazil.

Materials, Methods & Results: Records of 26 feline females, carriers of mammary neoplasms, were analyzed. Files from Veterinary Hospital of the Federal Rural University of Semi-Arid (located in the city of Mossoro, RN, Brazil) were used, comprehending the period from December 2004 to August 2009. The information collected was related to mammary tumor microscopic findings, obtained from classical histopathology reports. The lesions were distributed according to their biological behavior. Histological classification and morphological differentiation degree were also considered. Data related to neoplastic infiltration in adjacent tumoral regions were obtained as well. Descriptive statistic data were performed and submitted in percentage form. It was observed that most tumors (92%) exhibited malignant biological behavior. All of those were classified as carcinomas and, among the ones presenting benign behavior, intraductal papilloma was diagnosed. As referred to malignancies, the most common histological type corresponded to papillary carcinoma (42%). For morphological differentiation degree of mammary carcinomas, grade II presented the highest percentage (54%). Local tumor infiltration occurred mainly to the skin (75%).

Discussion: It has been reported that, among the palpable mammary masses in cats, 82% corresponded to malignancies and 10% were benign neoplasms. The data in discussion were not numerically equal to other researchers’ results, although agreeing with them in the sense that most neoplastic proliferations of feline mammary gland exhibited malignant biological behavior. This knowledge becomes important when addressing a cat carrying mammary mass, although additional tests are needed to confirm malignancy diagnosis. The frequency for different histological forms found in the experiment under discussion showed divergence in comparison to values stated in the literature. However, there was consensus regarding results in relation to the greater amount of papillary patterns. Regarding morphological differentiation degree, there were similarities to other researchers’ findings, which showed that the majority (57.8 to 60%) of feline mammary carcinomas belonged to grade II. Histological grading is a good parameter to stratify tumors according to their biological aggressiveness. Thus, this method is useful in the feline mammary neoplasia diagnosis, influencing the animals’ prognosis and survival time. It was reported that 42% of cats presented located metastases related to mammary carcinomas, since the behavior of such neoplasms is characterized by invasion of adjacent tissues and metastases to distant sites. It has been mentioned that skin, soft tissue, blood and lymph vessel infiltrations corresponded to adequate prognostic factors for mammary tumors, on microscopic level. As for the data under discussion, tumor spread to the skin site was fairly frequent. This could be justified because of the intimate contact between tumor and adjacent skin. The results obtained in the study under discussion fill a gap in relation to mammary tumor histopathological findings in cats from the state of RN, Brazil, in addition to providing useful information for veterinary practitioners and veterinary pathologists which are active in the region.