Composite signet-ring cell/neuroendocrine carcinoma of the stomach with a metastatic neuroendocrine carcinoma component: a better prognosis entity

BACKGROUND: Mixed (composite) exocrine-neuroendocrine cell carcinomas are defined as an intimate admixture of neoplastic glandular exocrine and neuroendocrine cell types. Although gastric adenocarcinoma containing a small number of neuroendocrine cells is a relatively frequent occurrence, gastric neoplasms containing equal proportions of both cell types are rare. CASE PRESENTATION: We present a case of composite exocrine (signet-ring cell)-neuroendocrine cell carcinoma, in which the neoplastic signet-ring cell exocrine and neuroendocrine constituents occurred in fairly equivalent amounts, whereas only the neuroendocrine carcinoma portion of the tumor represented the metastatic component. Light microscopy, immunohistochemical and electron microscopic findings are described, and the literature is reviewed. CONCLUSION: This study confirms the ability of pluripotent precursor cells to differentiate into either adenocarcinoma or neuroendocrine tumor and, justifying the designation of composite exocrine-neuroendocrine cell carcinoma as the appropriate classification for this tumor. The protracted clinical course further supports the notion that composite signet-ring cell/neuroendocrine carcinoma tumors behave relatively less aggressively than the pure forms of the former cell type.