In order to better characterize entotic figures in tumors, after the macroscopic examination of postoperative tissues (described in Materials and Methods, Section 4.4), we performed a descriptive immunohistochemical analysis of the Ki67 proliferation marker and selected epithelial–mesenchymal transition markers (vimentin, E-cadherin) in the studied case of double-negative HER2-positive NOS breast cancer. This evidence concerns the gene ERBB2 and breast cancer.