The patient was a 45-year-old woman with no significant medical history who presented with a self-palpated mass in the right breast for 4 months in 2018 (Figure 1). A right breast biopsy indicated grade 3 ductal invasive carcinoma that was ER– and PR– with equivocal results for HER2 by IHC but positive results with fluorescent in situ hybridization (FISH). The gene discussed is ESR1; the disease is invasive ductal breast carcinoma.