Microscopic Colitis (MC) is a rare pediatric problems and occurs when chronic diarrhea occurs in the presence of a normal-appearing endoscopic exam but with abnormal histology.  In adult populations, microscopic colitis is seen more frequently and can be confused with irritable bowel syndrome.  The two subtypes:

• Lymphocytic Colitis (LC):  >20 intraepithelial lymphocytes/100 colonocytes
• Collagenous Colitis (CC): thickened subeptihelial collagen band in addition to changes seen with LC

In a recent study (JPGN 2013; 57: 557-61), 27 MC cases were identified from a pathology database between 1995-2011.  5 were excluded due to an enteric infection.  Among the 22 other cases, 19 had LC and 3 had CC.  Association with celiac disease was evident in 4 patients and many had preceding drug exposures.

Treatment included steroids, melamine, an bismuth.

Additional references:

• -JPGN 2011; 53: 579. lymphocytic colitis case report
• -Clincal Gastro & Hep 2011; 9: 13.  Celaic with persistent symptoms: consider poor adherence**, SBBO*, pancreatic insufficiency*, refractory celiac (rare), PLE, giardia, malignancy, lactose intolerance, functional d/o*, microscopic colitis, Crohn’s*, NSAIDs
• -Gut 2009; 58: 68-72. Collagenous colitis: Budesonide at 6mg/day maintained remission in ~25%.
• Gastro 2008; 135: 1510.  Budesonide effective for collagenous colitis; n=48, 9mg/day.
• -Gastro 2011; 140: 1155. Review of microscopic colitis/collagenous colitis.
• -Am J Gastroenterol 2010; 105: 859-865.  n=466 & 451 controls.  Microscopic colitis present in 1.5% of IBS patients.  IBS pts with lower incidence of adenomas (7.7.% vs 26%).  9% had diverticulosis (lower).
• -Clin Gastro & hep 2009; 7: 1210. 4.3% of pts w microscopic colitis had celiac. 44/1009.