title: Expression of cytokeratins 7 and 20 in carcinomas of the gastrointestinal tract.
abstract: OBJECTIVE
  The differential expression of cytokeratin (CK) 7 and 20 by carcinomas may help in determining the primary site of a metastatic tumour. The aim of this study was to extend the published data on CK7 and CK20 expression in epithelial neoplasms of the gastrointestinal tract by considering the degree of differentiation and including some unusual neoplasms.
  
  
  RESULTS
  Cases referred to the Armed Forces Institute of Pathology were studied prospectively for immunohistochemical expression of CK7 and CK20. Lesions from 105 patients were analysed. Adenocarcinomas of the upper gastrointestinal tract were positive for both CK7 and CK20 in 78% of cases; only poorly differentiated lesions were CK7-. Well-differentiated and moderately differentiated adenocarcinomas of the large intestine, including appendix, were CK7-/CK20+ in the great majority of cases, as were goblet cell carcinoids, but half of the poorly differentiated adenocarcinomas exhibited aberrant expression, as did most of the mixed goblet cell carcinoid/adenocarcinomas. All five high-grade neuroendocrine carcinomas were negative for both CK7 and CK20.
  
  
  CONCLUSIONS
  Not only the site but also the grade and histological type of a gastrointestinal carcinoma should be considered when assessing cytokeratin phenotype.
authors.affiliation: Department of Hepatic and Gastrointestinal Pathology, Armed Forces Institute of Pathology, Washington, DC, USA.
authors.forename: A I
authors.initials: AI
authors.lastname: Kende
authors.forename: N J
authors.initials: NJ
authors.lastname: Carr
authors.forename: L H
authors.initials: LH
authors.lastname: Sobin
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism* / Q000473:pathology; D002276:Carcinoid Tumor / Q000378:metabolism* / Q000473:pathology; D005770:Gastrointestinal Neoplasms / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007124:Immunoenzyme Techniques; D007381:Intermediate Filament Proteins / Q000378:metabolism*; D053554:Keratin-20; D053552:Keratin-7; D007633:Keratins / Q000378:metabolism*; D009378:Neoplasms, Multiple Primary / Q000378:metabolism / Q000473:pathology; D011446:Prospective Studies
chemical_list: D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; C507497:KRT7 protein, human; D053554:Keratin-20; D053552:Keratin-7; D007633:Keratins