ERBB2 and breast cancer: Since, as far as we are aware, there are currently no morphological clues capable of making a pathologist suspect a possible mammary origin of a metastatic lesion in the brain in the absence of adequate clinical information, the histologic diagnosis of brain metastasis from BC is mainly based on the immunohistochemical expression of mammary gland markers such as GATA-3, ERs, progesterone receptors (PgRs) and HER-2 [7].