Her-2 expression in feline mammary lesions

Due to the high occurrence of mammary neoplasms in cats, the search for prognostic factors has recently intensified. Human epidermal growth factor receptor type 2 (Her-2) is prominent among the immunohistochemical markers used for prognosis. The aim of this study was to evaluate the expression of Her-2 in mammary lesions in queens and relate the expression to the type and histological grade of mammary carcinomas. Thirty-eight cases were selected from 2006 to 2016 and were classified and histologically graded. Her-2 expression was determined through immunohistochemistry, using a semi-quantitative analysis of the slides according to the scores recommended in the Dako HercepTest. Chi-square test was used to evaluate the relationship between Her-2 expression and mammary lesion type and the type and histological grade of carcinoma ( P < 0.05). The mean age was 8.5 years and young cats were affected only by benign hyperplasias and neoplasms. Undefined cats were more affected (84.37%), followed by Siamese (9.37%) and Persian (6.25%) cats. Regarding the histological classification, 18.42% of the mammary lesions were classified as hyperplasia, 18.42% as adenoma, and 63.16% as carcinoma. The most common type of carcinoma was tubulopapillary carcinoma (66.7%), followed by solid carcinoma (25%) and cribriform carcinoma (8.33%). Her-2 overexpression was observed in four samples (16.7%) of tubulopapillary carcinoma, two grade I carcinomas and two grade II carcinomas, but no relationship was observed between Her-2 expression and type of mammary lesion ( P = 0.3127), carcinoma type (0.3446), or histological grade (0.6485). In conclusion, Her-2 overexpression is unrelated to histological grade and type.