Microscopic colitis

Microscopic colitis typically presents in people >50 years with chronic, non-bloody, watery diarrhoea and is more common in women than in men. Other common symptoms include faecal urgency, faecal incontinence, and nocturnal stools. Symptoms can lead to a significantly impaired quality of life.

Most investigations are carried out to rule out other causes of chronic diarrhoea such as inflammatory bowel disease, coeliac disease, and irritable bowel syndrome.

Diagnosis of microscopic colitis is confirmed by the presence of characteristic pathohistological findings from ileocolonoscopy biopsies taken from the right and left colon. The colonic mucosa has a normal or near-normal gross appearance on ileocolonoscopy.

Treatment aims to achieve clinical remission (<3 stools per day and <1 watery stool per day) and improve quality of life. Drug choice depends on the severity and extent of disease and includes antidiarrhoeals, bismuth subsalicylate, oral budesonide, bile acid sequestrants, and immunosuppressants or biological agents. All patients should additionally have modification of contributing factors, including diet changes if appropriate, avoiding/withdrawing culprit medications, and encouraging cigarette smokers to cease.

Despite high rates of response to medical treatment, the relapse rate after discontinuation is 60% to 80% of patients with variable time to relapse. In patients with recurrent disease, consider re-treatment with prior therapies or with biologicals for patients with severe refractory symptoms.

Microscopic colitis is an inflammatory disease of the colon characterised by chronic watery, non-bloody diarrhoea and a normal or near-normal appearance on colonoscopy.[1]Miehlke S, Verhaegh B, Tontini GE, et al. Microscopic colitis: pathophysiology and clinical management. Lancet Gastroenterol Hepatol. 2019 Apr;4(4):305-14. http://www.ncbi.nlm.nih.gov/pubmed/30860066?tool=bestpractice.com It mostly affects older adults (>50 years) and is rare in children.[2]Münch A, Sanders DS, Molloy-Bland M, et al. Undiagnosed microscopic colitis: a hidden cause of chronic diarrhoea and a frequently missed treatment opportunity. Frontline Gastroenterol. 2019 Jul 5;11(3):228-34. https://fg.bmj.com/content/11/3/228 http://www.ncbi.nlm.nih.gov/pubmed/32419914?tool=bestpractice.com [3]Nguyen GC, Smalley WE, Vege SS, et al. American Gastroenterological Association Institute guideline on the medical management of microscopic colitis. Gastroenterology. 2016 Jan;150(1):242-6. https://www.gastrojournal.org/article/S0016-5085(15)01625-X/fulltext http://www.ncbi.nlm.nih.gov/pubmed/26584605?tool=bestpractice.com [4]Józefczuk J, Wozniewicz BM. Clear cell colitis: a form of microscopic colitis in children. World J Gastroenterol. 2008 Jan 14;14(2):231-5. https://www.wjgnet.com/1007-9327/full/v14/i2/231.htm http://www.ncbi.nlm.nih.gov/pubmed/18186560?tool=bestpractice.com Diagnosis is based on abnormal histological features from biopsies from the left and right colon.[1]Miehlke S, Verhaegh B, Tontini GE, et al. Microscopic colitis: pathophysiology and clinical management. Lancet Gastroenterol Hepatol. 2019 Apr;4(4):305-14. http://www.ncbi.nlm.nih.gov/pubmed/30860066?tool=bestpractice.com [5]Arasaradnam RP, Brown S, Forbes A, et al. Guidelines for the investigation of chronic diarrhoea in adults: British Society of Gastroenterology, 3rd edition. Gut. 2018 Aug;67(8):1380-99. https://gut.bmj.com/content/67/8/1380.long http://www.ncbi.nlm.nih.gov/pubmed/29653941?tool=bestpractice.com Microscopic colitis encompassess two major different subtypes based on histology: lymphocytic colitis and collagenous colitis.[6]Miehlke S, Guagnozzi D, Zabana Y, et al. European guidelines on microscopic colitis: United European Gastroenterology and European Microscopic Colitis Group statements and recommendations. United European Gastroenterol J. 2021 Feb 22;9(1):13-37. https://onlinelibrary.wiley.com/doi/10.1177/2050640620951905 http://www.ncbi.nlm.nih.gov/pubmed/33619914?tool=bestpractice.com Both subtypes typically have similar clinical features.[7]Tome J, Kamboj AK, Pardi DS. Microscopic colitis: a concise review for clinicians. Mayo Clin Proc. 2021 May;96(5):1302-8. https://www.mayoclinicproceedings.org/article/S0025-6196(21)00246-9/fulltext http://www.ncbi.nlm.nih.gov/pubmed/33958059?tool=bestpractice.com There is a subset of patients who do not meet histological criteria; these patients may be diagnosed as 'microscopic colitis not otherwise specified' or 'microscopic colitis incomplete'.[1]Miehlke S, Verhaegh B, Tontini GE, et al. Microscopic colitis: pathophysiology and clinical management. Lancet Gastroenterol Hepatol. 2019 Apr;4(4):305-14. http://www.ncbi.nlm.nih.gov/pubmed/30860066?tool=bestpractice.com [8]Münch A, Aust D, Bohr J, et al. Microscopic colitis: current status, present and future challenges: statements of the European Microscopic Colitis Group. J Crohns Colitis. 2012 Oct;6(9):932-45. https://academic.oup.com/ecco-jcc/article/6/9/932/2392159 http://www.ncbi.nlm.nih.gov/pubmed/22704658?tool=bestpractice.com

This topic covers microscopic colitis in adults.