Microscopic & Radiation Colitis
MICROSCOPIC COLITIS (Am J Gastroenterol 2004, 94:451-65)
Definition:
Idiopathic colitides with mild inflammatory changes diagnosed only by colorectal biopsy and thus only microscopically
Microscopic colitis is an umbrella term encompassing both Collagenous and Lymphocytic Colitis
Collagenous Colitis: | Lymphocytic Colitis: | |
|---|---|---|
Gender incidence (F:M) | 5:1 | 1:1 |
HLA B27 Positive | No | Yes |
Histology: | ||
-Increased intraepithelial lymphocytes | Yes | Yes |
-Increased lymphocyte lamina propria | Yes | Yes |
-Surface epithelial flattening | Yes | Yes |
-Thickened subepithelial collagen band | Yes | No |
Epidemiology:
Collagenous Colitis: 1/100,000; Most common with females, age 50-60
Lymphocytic Colitis: 3/100,000; Equal in both male/female
Both are far less common than IBD
Pathophysiology:
Collagenous Colitis
Diagnostic triad: increased intraepithelial lymphocytes, flattened surface epithelium, thickened subepithelial collagen band
Lymphocytic Colitis
Increased intraepithelial lymphocytes, flattened surface epithelium but without subepithelial collagen band
Biopsies also show no crypt architecture distortion (IBD has distortion of crypt architecture)
Can affect any part of colon; Patchy in nature
MOA (theory): Autoimmune (both) and NSAIDs (Collagenous only); Other theories: bile acid malabsorption, unidentified infectionRelated posts:
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