In our study, the rate of incidence of NI was 12.6% in mastectomy patients, and the associated clinicopathologic characteristics included nipple signs, tumor location, tumor size measured by ultrasound or gross pathologic samples, tumor–nipple distance, lymph node metastasis, and HER2 overexpression. This evidence concerns the gene ERBB2 and metastatic malignant neoplasm in the lymph nodes.