title: Mucin phenotype expression of gastric neuroendocrine neoplasms: analysis of histopathology and carcinogenesis.
abstract: BACKGROUND
  Gastric neuroendocrine neoplasia has been classified as neuroendocrine tumor (NET), a less-malignant type, and neuroendocrine carcinoma (NEC), a more-malignant type. We investigated phenotypic expression profiles to clarify the differences between NET and NEC in terms of histopathology and carcinogenesis.
  
  
  METHODS
  We assayed 86 cases of gastric neuroendocrine neoplasms (NET G1, n = 25; NET G2, n = 9; NEC, n = 52), using six exocrine markers (MUC5AC, human gastric mucin, MUC6, M-GGMC-1, MUC2, and CDX2).
  
  
  RESULTS
  NEC frequently coexisted with adenocarcinomatous components (75 %; 39 of 52) and the majority (71.8 %; 28 of 39) showed intraglandular endocrine cell hyperplasia, although no cases of NET showed adenocarcinomatous components. Mucin phenotype significantly differed between NET and NEC; none of NET cases expressed any exocrine markers other than CDX2, although the majority of NEC (86.5 %; 45 of 52) expressed at least one or more exocrine markers with various positive rates for each marker (range, 8.2-74.0 %). Each NEC component showed only the phenotype expressed in the adenocarcinomatous component in the same tumor. Furthermore, double immunohistochemistry revealed dual expression of CDX2 and chromogranin A in half the NEC cases (23 of 46).
  
  
  CONCLUSIONS
  These data suggest that gastric NETs (G1 and G2) and NECs have different processes of carcinogenesis, and gastric NECs may be generated from preceding adenocarcinomas.
authors.affiliation: Division of Molecular and Diagnostic Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan, doumori-nii@umin.ac.jp.
authors.forename: Koji
authors.initials: K
authors.lastname: Domori
authors.forename: Ken
authors.initials: K
authors.lastname: Nishikura
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Ajioka
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Aoyagi
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D000071616:CDX2 Transcription Factor; D063646:Carcinogenesis; D018278:Carcinoma, Neuroendocrine / Q000378:metabolism / Q000473:pathology*; D005260:Female; D005500:Follow-Up Studies; D005752:Gastric Mucins / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D055271:Mucin 5AC / Q000378:metabolism; D055262:Mucin-2 / Q000378:metabolism; D055272:Mucin-6 / Q000378:metabolism; D009367:Neoplasm Staging; D018358:Neuroendocrine Tumors / Q000378:metabolism / Q000473:pathology*; D010641:Phenotype; D011379:Prognosis; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology*
chemical_list: D014408:Biomarkers, Tumor; D000071616:CDX2 Transcription Factor; C491270:CDX2 protein, human; D005752:Gastric Mucins; D018398:Homeodomain Proteins; D055271:Mucin 5AC; D055262:Mucin-2; D055272:Mucin-6