We examined the histological phenotypes of a composite gastric tumor consisting of AFPC/HAC, NEC, and tubular adenocarcinoma and investigated the cellular phenotypes of AFPC and NEC by evaluating the immunohistochemical expressions of MUC2, MUC5AC, MUC6, CDX2, and SOX2. This evidence concerns the gene MUC6 and neuroendocrine carcinoma.