An immunohistochemical analysis of the breast tumor showed ER (+), PgR (+), HER2 (3+), and E-cadherin (−) (Fig. 3a), while that of the appendiceal tumor showed ER (+), PgR (−), HER2 (3+), and E-cadherin (−) (Fig. 3b). The gene discussed is CDH1; the disease is breast neoplasm.