Male breast cancer (MBC) is a rare disease. One out of 150 cases of breast cancer is expected to occur in the male gender. Due to the low incidence of this neoplasia, most information about it derives from female breast carcinoma, whose diagnostic, prognostic and therapeutical parameters are well established in the medical literature. However, the distribution of molecular phenotypes of male breast carcinomas is little known. We analyzed the clinical and immunohistochemical data of a sample comprising 20 cases of invasive male breast tumor. We used a panel of five antibodies that encompasses estrogen receptor, cytokeratins 5/6, cytokeratins 8/18, HER1 and HER2. Among these 20 cases, 19 were non-special ductal carcinomas (95%) and one was a lobular carcinoma (5%). Most cases were mastectomies (65%) and the average size of the neoplasias was 2.8 cm. The most frequent histological grade was II (60%). Axillary lymph node metastases were presented by 86.6% of the total cases. The average number of affected lymph nodes was 5.2 in the samples with positive nodes. Fourteen tumors corresponded to ER+/luminal phenotype (70%), two were classified as undetermined (10%), one (5%) belonged to the basal phenotype and three breast tumors (15%) corresponded to HER2-positive phenotype. The immunohistochemical results of the male breast carcinomas allow us to make comparisons with female breast tumors, what may elucidate the intrinsic factors of the disease in each gender.
Male breast cancer; Immunohistochemistry; Immunophenotyping