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Pathology of Microscopic Colitis-

Collagenous Colitis

Dr Sampurna Roy MD


Pathology Quiz Case 38:Case History and images

Diagnosis: Collagenous Colitis



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Microscopic Colitis includes two disease conditions - Collagenous Colitis and Lymphocytic Colitis.

These conditions are characterized by watery diarrhea, normal colonoscopy findings and characteristic histopathological features.

Collagenous colitis is characterized by a conspicuous subepithelial collagenous band (more than 10 micrometer).

The collagenous thickening is highlighted by Masson trichrome stains. 

(The eosinophilic band is negative for amyloid).

The inflammatory changes parallel the collagen deposition.

In lymphocytic colitis there is absence of thickened collagenous layer. 

In both collagenous and lymphocytic colitis there is an increase in intra-epithelial lymphocytes (more than 20 lymphocytes per 100 epithelial cells  compared to the normal value of 5 lymphocytes per 100 epithelial cells) and a moderate to marked increase in mononuclear cells (plasma cells and lymphocytes) in the lamina propria.

Clusters of chronic inflammatory cells are present at the base of the crypts. 

Some eosinophils and mast cells are often present deep in the mucosa. 

The crypt architecture and goblet cells  are usually well preserved with no cryptitis or crypt abscess formation. 

Some cases have been reported  showing minimal crypt architectural  distortion, some goblet cell depletion, presence of neutrophils and focal surface epithelial damage. 

In many of the documented cases of microscopic colitis there are overlapping features of both lymphocytic and collagenous colitis.

There is striking histological similarities between coeliac disease and both collagenous and lymphocytic colitis.

Recently non-necrotizing pericryptal granulomas have been described in cases of microscopic colitis.

These cases should not be confused with Crohn's disease.

It has been reported that Tenascin is a useful marker in the diagnosis of collagenous colitis.

Note:  Tangential sectioning of normal colon can result in artifactual thickening of the basement membrane.

Hence in the absence of the characteristic inflammatory pattern tangentially cut colonic biopsies should not be diagnosed as collagenous colitis.

Some authors have divided microscopic colitis into

-Classical - collagenous colitis, lymphocytic colitis  and 

-Non-classical - granulomatous colitis, giant-cell microscopic colitis, pseudo-membranous microscopic colitis.

Visit: Collagenous Gastritis     


Further reading:

Microscopic colitis with giant cells: a rare new histopathologic subtype?

Sequential clinical and histopathological changes in collagenous and lymphocytic colitis over time.

Microscopic colitis with granulomatous inflammation.

Microscopic colitis: pathologic considerations, changing dogma.

Diagnosis and management of microscopic colitis syndrome.

The terminal ileum is affected in patients with lymphocytic or collagenous colitis.

Collagenous colitis: a study of the distribution of morphological abnormalities and their histological detection.

Microscopic colitis syndrome: lymphocytic colitis and collagenous colitis.

Collagenous colitis: a practical orientated approach to diagnosis.

Tenascin labelling in colorectal biopsies: a useful marker in diagnosis of  collagenous colitis.

Chronic, unexplained diarrhea: are biopsies necessary if colonoscopy is normal?

Collagenous colitis and microscopic colitis: the watery diarrhea-colitis syndrome.

Biopsies of the endoscopically normal rectum and colon; a necessity. Incidence of collagen colitis and microscopic colitis.



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Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)






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