Abstract
BackgroundMixed (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 PresentationWe 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.ConclusionThis 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.
Highlights
Mixed exocrine-neuroendocrine cell carcinomas are defined as an intimate admixture of neoplastic glandular exocrine and neuroendocrine cell types
Diagnostic Pathology 2007, 2:43 http://www.diagnosticpathology.org/content/2/1/43 et al [4] reclassified the mixed endocrine and nonendocrine epithelial tumors by subdivision into six categories: 1) neuroendocrine cells interspersed within carcinomas; 2) carcinoids with interspersed nonendocrine cells; 3) composite glandular-neuroendocrine cell carcinomas containing both areas of carcinoid and conventional carcinoma; 4) collision tumors in which neuroendocrine tumors and conventional carcinomas are closely juxtaposed but not admixed; 5) amphicrine tumors predominantly composed of cells exhibiting concurrent neuroendocrine and nonendocrine differentiation; and 6) combinations of the previous types
Present a case of a composite glandular-neuroendocrine carcinoma of the stomach emphasizing the light microscopy, immunohistochemical and electron microscopic characteristics of the tumor as well as the clinicopathological correlations
Summary
In the present study it was determined by light microscopy that the neoplastic cell population contained equal amounts of both tumor components, displaying on the one hand a typical signet-ring cell adenocarcinoma pattern admixed with clusters of small cells consistent with neuroendocrine differentiation on the other. Due to the fact that the NET component in the current case was significantly larger than 2 cm and had metastasized to a group of matted lymph nodes located adjacent to the lesser curvature of the stomach, we can hypothesize that this tumor would behave similar to a well-differentiated neuroendocrine carcinoma based on the WHO classification [11]. This was a very unusual finding, given that the NEC (malignant carcinoid) component was metastatic without any participation of the signet-ring cell component, even if the latter is typically the more malignant tumor. As recently emphasized in cases of advanced signet-ring cell carcinoma with better prognosis than expected [2], the diagnosis of composite glandular/neuroendocrine tumor needs to be considered
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