Histologic and immunohistochemical analysis revealed that all HER2 heterogeneous breast cancers subjected to microdissection were ER-positive (as defined by the current cutoff of >1% of ER-positive cells [25] in the whole tumor), and eight cases were also progesterone receptor (PR)-positive (Figure 1A; Additional file 1). This evidence concerns the gene ERBB2 and breast carcinoma.