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Author: Mikael Häggström [notes 1]


On this resource, the following formatting is used for comprehensiveness:

  • Minimal depth
  • (Moderate depth)
  • ((Comprehensive))

Microscopic evaluation

Also look for collagenous colitis, with a thickened subepithelial collagen band that is typically more than 10 μm in thickness.[1]
  • Look for signs of active (or acute) and/or chronic colitis:

Signs of active (or acute) colitis:

  • Neutrophilic cryptitis
  • Neutrophilic crypt abscesses
  • Ulceration or granulation tissue
  • Ischemic changes (including superficial necrosis, hemorrhage, crypt shrinkage/dropout, fibrin thrombi)

Signs of chronic colitis:

  • Abnormal crypt orientation a
  • Abnormal crypt branching
  • Paneth cell or gastric metaplasia (only apllies in the left colon and rectum)
  • Elevation of crypts relative to the muscularis mucosa

(Consider the clinical and/or endoscopic finding in the evaluation.)

Further workup of colitis


  • Distribution: Patchy versus diffuse
  • Severity: Mild, moderate or severe
  • Presence of crypt regeneration, granuloma, inflammatory pseudomembranes, parasites, viral inclusions or epithelial dysplasia.

Microscopy report

Example of a normal sample, when colitis was suspected in the referral:

( Optionally: Colonic/Rectal mucosa without significant histopathologic changes.) Negative for acute and chronic colitis.

Example of findings of both active and chronic colitis:

(Ascending, transverse, descending, and sigmoid colon, biopsies:) Mild chronic active colitis, with associated cryptitis and crypt abscesses. (Negative for ulceration, granulomata and dysplasia.)


  1. For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.

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  1. Benjamin J. Van Treeck, M.D., Catherine E. Hagen, M.D.. Collagenous colitis. Pathology Outlines. Topic Completed: 3 August 2020. Minor changes: 29 September 2020