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Gastric cancer (GC) is rich in many different histological types, but how the histological pattern is defined remains to be proved. The relation between GC histological types and the expression of nectin1, which is one of the cell adhesion molecules that composes adherens junction, has not been reported. According to a publicly available database of 406 GC patients, the median overall survival of Nectin1 high expression patients was 55.4 months and that of low expression patients was 25.6 months (P = 0.0246). Using surgically or endoscopically resected GC samples, nectin1 expression was analyzed by immunohistochemistry. Nectin1 expressed at adherens junction in all the normal epithelial cells. However, nectin1 expressed not at adherens junction but at apical membrane in epithelial cells in intestinal metaplasia. The expression pattern of nectin1 in intestinal type GC resembled to intestinal metaplasia. In order to analyze the difference in nectin1 expression between GC histological types, a total of 116 intestinal type GC and 33 diffuse type GC. The expression of necitin1 in diffuse type GC (3.0%) was remarkably decreased compared to that in intestinal type GC (65.5%) (P < 0.0001). In conclusion, this is the first report showing an association between nectin1 expression and histological subtypes of GC.

Glioneuronal tumor (GNT) is a rare central nervous system neoplasm composed of glial and neuronal components. Making the specific diagnosis of GNT can be challenging due to histopathological and genetical similarities among some GNTs and low-grade gliomas. We report a case of GNT with rosette-forming glioneuronal tumor, dysembryoplastic neuroepithelial tumor, and pilocytic astrocytoma-like morphology harboring FGFR1 mutation. A 16-year-old female presented with absence seizures. Magnetic resonance imaging revealed a right temporal lobe mass with multinodular enhancement by gadolinium administration. The tumor was mostly composed of oligodendrocyte-like cells (OLCs) with variable perinuclear haloes. Abundant Rosenthal fibers and eosinophilic granular bodies were identified. Neither mitotic figures nor areas of necrosis were seen. Focal neurocytic rosette features, involving ring-like arrays of OLCs around eosinophilic cores, were observed. Direct sequencing showed a missense mutation in FGFR1 K656E, whereas FGFR1 N546K, PIK3CA, and BRAF V600E were intact. KIAA1549-BRAF fusion was not detected by fluorescence in situ hybridization analysis.