title: Obliterative muscularization of the small bowel submucosa in Crohn disease: a possible mechanism of small bowel obstruction.
abstract: BACKGROUND
  The pathology of small bowel obstruction in Crohn disease has not been studied extensively. Stricture formation has been attributed mainly to fibrosis, although muscularization of the submucosa has been discussed previously.
  
  
  OBJECTIVE
  To identify additional pathologic changes in Crohn disease that could be involved in the formation of strictures.
  
  
  METHODS
  We reviewed 50 ileal resections from patients with Crohn disease. The histopathologic slides were reviewed initially without knowledge of the macroscopic or clinical findings. We identified an unusual muscular proliferation that we refer to as obliterative muscularization of the submucosa, defined as a thick and continuous muscle layer from the mucosal base to the muscularis propria that is at least 1 cm in length. Subsequently, histopathologic findings were correlated with macroscopic and clinical findings.
  
  
  RESULTS
  Obliterative muscularization of the submucosa was present in 14 specimens, and in 11 of these 14 it was topographically restricted to strictures. Submucosal fibrosis was observed in sections from adjacent regions. Obliterative muscularization of the submucosa, including thick-walled vessels and hyperplastic nerves but not prominent scarring, was more common in specimens with strictures; the difference was statistically significant (P <.001).
  
  
  CONCLUSIONS
  Obliterative muscularization of the submucosa may be pathogenetically involved in the formation of strictures either directly by causing a sustained spasm, or indirectly by minimizing the vasoprotective role of the submucosa, impairing repair and enhancing scarring.
authors.affiliation: Department of Pathology, School of Medicine, Indiana University, Indianapolis, USA. gkoukoul@iupui.edu
authors.forename: G
authors.initials: G
authors.lastname: Koukoulis
authors.forename: Y
authors.initials: Y
authors.lastname: Ke
authors.forename: J D
authors.initials: JD
authors.lastname: Henley
authors.forename: O W
authors.initials: OW
authors.lastname: Cummings
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003424:Crohn Disease / Q000473:pathology* / Q000601:surgery; D005260:Female; D005355:Fibrosis; D006099:Granuloma / Q000473:pathology; D006801:Humans; D007082:Ileum / Q000473:pathology / Q000601:surgery; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000473:pathology*; D007421:Intestine, Small / Q000473:pathology*; D008297:Male; D008679:Metaplasia; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology*; D014456:Ulcer / Q000473:pathology