Immunohistochemical (IHC) analysis revealed HER2 (0), MLH1(+), MSH2(+), MSH6(+), PMS2(+), PD‐1(+), while other markers indicated CgA(+), Syn(+), histologically characterizing the tumor as neuroendocrine carcinoma with a MIB‐1 index of 60% in tumor cells. The gene discussed is MSH2; the disease is neoplasm.