Combined with preoperative pathological puncture results (Fig. 2C and D) and immunohistochemical phenotyping: tumor cells were negative for estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor-2, calponin, Syn, CD56, CgA, and CK5/6; positive for P120 (membrane +), E-Cadherin, p63, EGFR, BRCA1, and TRPS-1 were positive; CD117, CK8/18, PAS, AB, and CD117 were partially positive; and the Ki-67 positivity index was 50%, which led to the diagnosis of triple-negative breast cancer. The gene discussed is ESR1; the disease is triple-negative breast carcinoma.