title: Carcinoids and endocrine cell micronests of the minor and major duodenal papillae. Their incidence and characteristics.
abstract: BACKGROUND
  There have been no reports about the incidence and characteristics of carcinoids and endocrine cell micronests (ECM) of the minor and major duodenal papillae.
  
  
  RESULTS
  The minor and major duodenal papillae of 78 consecutive autopsy and 117 surgical specimens were examined histologically using mirror-image paraffin-embedded tissue samples. ECM were found frequently in these areas in hematoxylin and eosin-stained sections, and their aggregation patterns were classified into four types: nodular type (Type 1, 2 of 167 in the minor papilla and 1 of 145 in the major papilla), scattered type (Type 2, 39 of 167 and 6 of 145), orifice type (Type 3, 7 of 167 and 0 of 145), and islet-like type (Type 4, 14 of 145 and 0 of 145, respectively). Criteria of neoplastic or nonneoplastic ECM were defined tentatively by histologic and immunohistochemical analyses of the ECM. Type 4 was regarded to be atrophic or regenerating islets of Langerhans. Distinct carcinoids (Type 1), neoplastic ECM (39% of all Type 2 and 3), and nonneoplastic ECM (61% of all Type 2 and 3) were found in 1.2%, 9.0%, and 16.2% of 167 samples of the minor papilla and 0.7%, 1.4%, and 2.8% of 145 specimens of the major papilla, respectively. The endocrine cells composing the carcinoids and the ECM usually were immunoreactive for somatostatin and/or pancreatic polypeptide (PP). They were negative for S-100 beta.
  
  
  CONCLUSIONS
  In duodenal papillae, especially in the minor duodenal papilla, carcinoids and ECM seem to occur more frequently than generally thought, and predominantly consist of somatostatin and/or PP containing cells.
authors.affiliation: First Department of Pathology, Niigata University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Noda
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Iwafuchi
authors.forename: K
authors.initials: K
authors.lastname: Furuta
authors.forename: N
authors.initials: N
authors.lastname: Ishihara
authors.forename: M
authors.initials: M
authors.lastname: Satoh
authors.forename: Y
authors.initials: Y
authors.lastname: Ajioka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014670:Ampulla of Vater / Q000166:cytology* / Q000648:ultrastructure; D002276:Carcinoid Tumor / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D003138:Common Bile Duct Neoplasms / Q000473:pathology*; D004702:Endocrine Glands / Q000166:cytology* / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008297:Male; D008875:Middle Aged; D010183:Pancreatic Ducts / Q000166:cytology* / Q000648:ultrastructure; D010190:Pancreatic Neoplasms / Q000473:pathology*