Other colitis: microscopic, diversion, GVHD, drug
- Lesion
Several kinds of colitis cause diarrhoea with a normal-looking colon; only the biopsy reveals collagen bands, lymphocytes or dying cells.
What it is
Some forms of colitis are defined mainly by histology. Diversion colitis develops in a segment bypassed by an ostomy. Microscopic colitis (collagenous and lymphocytic) causes chronic watery diarrhoea with a normal endoscopy. Graft-versus-host disease and apoptotic colitis from drugs such as immune checkpoint inhibitors and mycophenolate are marked by epithelial apoptosis.
Histology-defined colitides
| Type | Setting | Key histology | Endoscopy |
|---|---|---|---|
| Diversion colitis | Segment bypassed by an ostomy | Many mucosal lymphoid follicles | Red, friable |
| Collagenous colitis | Older women | Thick subepithelial collagen plus intraepithelial lymphocytes | Normal |
| Lymphocytic colitis | Coeliac disease, autoimmunity, drugs | Many intraepithelial lymphocytes, normal collagen | Normal |
| Graft-versus-host disease | After allogeneic stem cell transplant | Crypt apoptosis, crypt loss, sparse infiltrate | Variable, may be normal |
| Apoptotic (drug) colitis | Checkpoint inhibitors, mycophenolate | Increased epithelial apoptosis | Variable |
Clinical notes
- Chronic watery diarrhoea with a normal colonoscopy calls for random biopsies.
- Checkpoint-inhibitor colitis may be severe enough to stop cancer treatment.
Test yourself
Think of the answer, then tap the question to see it.
What defines collagenous colitis histologically?
A thickened subepithelial collagen band with increased intraepithelial lymphocytes and lamina propria inflammation.
What is the most common histological finding in intestinal graft-versus-host disease?
Epithelial apoptosis, especially of crypt cells, with relatively sparse inflammation.
Why does diversion colitis resolve after the ostomy is closed?
Faecal flow returns, restoring nutrients such as bacterial short-chain fatty acids to the colonocytes.
Elsewhere in DurgiPedia
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Ulcerative Colitis (StatPearls (NCBI Bookshelf), 2025).
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Representative model, for educational purposes only.