Her subsequent left breast skin punch biopsy demonstrated invasive carcinoma involving the epidermis and dermis, supporting a diagnosis of invasive ductal carcinoma with focal features of metaplastic squamous cell carcinoma, Nottingham grade 3, which was estrogen, progesterone, and human epidermal growth factor receptor 2 (HER2) negative. This evidence concerns the gene ERBB2 and invasive ductal breast carcinoma.