ESR1 and breast carcinoma: Correlation of the microscopic features of breast cancer with IHC of ER, PR and HER2 is, therefore, recommended [1,2]. Such correlating histological features are limited, however, to only a small subset of breast cancers (low-grade carcinoma, some special types). Additional morphological features showing association with ER/PR or HER2 in breast cancers, especially in the higher grades, would provide further help in the correlation of the microscopic patterns of breast cancer with ER/PR and HER2.