Elastosis in ERα-positive male breast cancer

In female breast cancer (BC), elastosis is strongly related to estrogen receptor alpha (ERα) expression. Male breast cancers almost invariably express ERα; so, the aim of this study was to investigate elastosis frequency in invasive male BC as well as clinicopathological correlations, in comparison with females. A total of 177 male BC cases and 135 female BC cases were included, all ERα-positive and invasive carcinoma of no special type. Elastosis on H&E-stained slides was scored in a four-tiered system as elastosis grade (EG) 0 (no elastosis) to EG3 (high amount of elastosis). EG scores in male BC were correlated to histopathological characteristics and overall surviva and compared with female BC EG scores. Male BC showed some degree of elastosis in 26/117 cases (22.2%) with none showing EG3, while female BC cases showed elastosis in 89/135 cases (65.9%) with 21.5% showing EG3 (p < 0.001). This difference retained its significance in multivariate logistic regression. In male BC cases, no significant correlations were found between the amount of elastosis and age, grade, mitotic activity index, and PgR. In addition, no significant prognostic value of elastosis was seen. In conclusion, despite high ERα expression, male BC showed significantly less elastosis than female BC. Elastosis did not show clinicopathological correlations or prognostic value. Therefore, elastosis seems to be a less useful ERα tissue biomarker with less clinical significance in male BC compared with females, pointing towards important BC sex differences.