Crohn disease: phases

nonstenotic phase:
- blunting, flattening, distortion, straightening, and thickening of mucosal folds (early event from obstructive lymphadema)
- aphthous ulcers: nodules with shallow central ulcerations
- "cobblestoning": serpiginous ulcers separated by areas of edema
- pseudopolyps: hyperplastic mucosa between denuded mucosa
- postinflammatory polyps
- "skip lesions" (90%)
- pseudodiverticula: bulging area of normal wall opposite affected scarred wall, mostly on the antimesenteric side
- separation and displacement of small bowel loops (from increase in mesenteric fat, enlarged nodes, or perforation with abscess formation)
stenotic phase:
- "string sign": strictures (most in TI) in rigid loops
- normal proximal loops may be dilated with stasis ulcers and fecoliths

Yong H. Hahn, MD - 2 February 1995
Last updated: 1 October 2013