ESR1 and metaplastic breast carcinoma: She developed a local chest wall recurrence, biopsy showing a metaplastic breast carcinoma with a component of pleomorphic lobular carcinoma associated with squamous differentiation, ER 20%, PR-, HER2- (IHC 1+ ISH 2.3, ratio 1.1), with androgen receptor staining positive in 30% of tumor cells.