Colitis

Author: Mikael Häggström
Most commonly found by endoscopic gastrointestinal biopsies.

Comprehensiveness

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

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

Microscopic evaluation

• Look for signs of active (or acute) and/or chronic colitis:

Signs of active (or acute) colitis:

• Neutrophilic cryptitis (neutrophils within crypt epithelium)
  Neutrophilic cryptitis (neutrophils within crypt epithelium)
• Crypt abscesses (luminal neutrophilic aggregates)
  Crypt abscesses (luminal neutrophilic aggregates)
• In fact, one neutrophil is enough for the feature
  In fact, one neutrophil is enough for the feature
• Normal mucosal fold for comparison
  Normal mucosal fold for comparison
• Gland destruction
  Gland destruction
• Ulceration (seen here as absence of epithelium, and granulation tissue with many fibroblasts)
  Ulceration (seen here as absence of epithelium, and granulation tissue with many fibroblasts)

Active colitis may also cause ischemic changes (including superficial necrosis, hemorrhage, crypt shrinkage/dropout, fibrin thrombi)

Signs of chronic colitis:

• Crypt degeneration
  Crypt degeneration
• Crypt branching and other architectural distortions
  Crypt branching and other architectural distortions
• Paneth cell (pictured) or gastric metaplasia (only applies in the left colon and rectum)
  Paneth cell (pictured) or gastric metaplasia (only applies in the left colon and rectum)

Chronic colitis may also cause elevation of crypts relative to the muscularis mucosa. Other findings include basal plasmacytosis and mucin depletion.

Have a high threshold for chronic colitis in the rectum, as it often shows chronic changes even without any disease.

In addition, look for the following types of colitis:

• Lymphocytic colitis, characterized by > 20 intraepithelial lymphocytes per 100 epithelial cells, away from lymphoid aggregates.[2]
  Lymphocytic colitis, characterized by > 20 intraepithelial lymphocytes per 100 epithelial cells, away from lymphoid aggregates.
• Lymphocytic colitis also shows increased lymphocytes, plasma cells, eosinophils, and occasional neutrophils in lamina propria, but with preserved architecture
  Lymphocytic colitis also shows increased lymphocytes, plasma cells, eosinophils, and occasional neutrophils in lamina propria, but with preserved architecture
• Collagenous colitis, with a thickened subepithelial collagen band that is typically more than 10 μm in thickness.[3]
  Collagenous colitis, with a thickened subepithelial collagen band that is typically more than 10 μm in thickness.
• Compare to normal colonic mucosa, which can have a band of basal epithelial cytoplasm.
  Compare to normal colonic mucosa, which can have a band of basal epithelial cytoplasm.

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

Further workup of colitis

Distinguish:

• (Severity: Mild, moderate or severe.)
• Presence of crypt regeneration, granuloma, inflammatory pseudomembranes, parasites or viral inclusions.
• Presence of epithelial dysplasia or even cancer. If unsure of the latter, consider immunohistochemistry for cytokeratins such as CK AE1/AE3. Further information: Evaluation of suspected malignancies
• ((Distribution: Patchy versus diffuse))

• A non-necrotizing granuloma. It is seen as an aggregate of histiocytes in the center of the image, having ample eosinophilic cytoplasm.
  A non-necrotizing granuloma. It is seen as an aggregate of histiocytes in the center of the image, having ample eosinophilic cytoplasm.
• Dysplastic crypt at right. In such case, consider tubular and ⁄or villous adenoma.
  Dysplastic crypt at right. In such case, consider tubular and ⁄or villous adenoma.
• Look particularly in ulcers for signet ring cells.
  Look particularly in ulcers for signet ring cells.

Apart from histologically defined diagnoses (collagenous colitis, lymphocytic colitis), there is no need to speculate about the exact underlying diagnosis (such as Crohn's disease, ulcerative colitis etc.).

Microscopy report

A biopsy report generally does not state the diagnosis, but should state any presence of chronic colitis, give an indication of disease activity, as well as state the presence of any epithelial damage (erosions and ulcerations).

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

(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:) ((Patchy)) (mild) chronic active colitis((, with associated cryptitis and crypt abscesses.)) (Negative for ulceration, granulomata and dysplasia.)

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