May 2016 Case of the Month

69 year-old woman presents with chronic diarrhea.  An endoscopic random colon biopsy is performed.  What is your diagnosis?

4x
4x

Low power view shows fragments of colonic mucosa with focal pale eosinophilic thickening of the subepithelial collagen table.

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10x
10x

Arrows highlight areas where thickening is pronounced and hyalinized in appearance. Notably, intraepithelial lymphocytosis is largely lacking.

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10x Trichrome
10x Trichrome

A trichrome stain highlights the band of excess subepithelial collagen.

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4x
4x

Low power view shows fragments of colonic mucosa with focal pale eosinophilic thickening of the subepithelial collagen table.

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May 2016 Case of the Month

   Answer: Collagenous Colitis

Collagenous colitis (CC) is one of the microscopic colitides (along with lymphocytic colitis) that typically affects middle-aged to older females with chronic diarrhea.  Although not well understood, some luminal antigen(s) are thought to be involved in the pathogenesis of CC.  Studies have also shown a strong association with the use of NSAIDs and with celiac disease.  Some patients with CC have spontaneous remission, while others respond to the use of over the counter anti-diarrheal agents.  Still other patients require anti-inflammatory therapies such as steroids or aminosalicylic acid compounds.