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What Is Microscopic Colitis?

Collagenous Colitis And Lymphocytic Colitis Are Not Related To IBD

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Updated January 27, 2014

Microscopic colitis is actually two similar but separate conditions: collagenous colitis and lymphocytic colitis. Although they have “colitis” in their name, these conditions are not related to ulcerative colitis or Crohn’s disease (collectively known as inflammatory bowel disease, or IBD).

People in their 50s are the group that are most often diagnosed with collagenous colitis. The condition tends to affect more women than men. The average age of onset for lymphocytic colitis is in the 60s, and women seem to be affected slightly more often than men.

Microscopic colitis has not been extensively researched, so it's still unknown as to how common it is.

Causes Of Microscopic Colitis

The cause of microscopic colitis is currently unknown (it is an idiopathic disease). One theory is that the use of non-steroidal-anti-inflammatory drugs (NSAIDs, such as ibuprofen) may contribute to the development of microscopic colitis. Another theory is that microscopic colitis is caused by an autoimmune response, where the body’s immune system attacks other tissues in the body.

It is also theorized that bacteria or viruses may play a role in the development of microscopic colitis. As of now, the exact relationship and mechanism of this cause is unknown.

Signs and Symptoms Of Microscopic Colitis

The hallmark symptoms of microscopic colitis are chronic, watery diarrhea, sometimes accompanied by cramps and abdominal pain. The diarrhea could range from being continuous and severe to intermittent in nature. Blood in the stool, which is a common symptom of ulcerative colitis, is not a symptom of microscopic colitis.

Other symptoms could include fever, joint pain, and fatigue. These symptoms may be a result of the inflammatory process that is part of an autoimmune disease.

Diagnosis Of Microscopic Colitis

In microscopic colitis, the colon generally appears normal on sight. Therefore, a colonoscopy or sigmoidoscopy might not show any evidence of disease. In some patients there may be areas of swelling or redness in the colon, but these may be difficult to see.

In order to make a diagnosis, several biopsies must be taken from the colon during a colonoscopy. These biopsies will preferably come from several different areas in the colon. The hallmark signs of the disease can then be seen microscopically on biopsy tissue, hence the name of “microscopic” colitis.

Collagen is a substance that is normally present under the lining of the colon. In collagenous colitis, biopsy tissue will show larger than normal amounts of collagen beneath the lining of the colon. A biopsy may also show an increased number of lymphocytes -- a type of white blood cell.

In lymphocytic colitis, examination of a biopsy will show increased numbers of lymphocytes in the colon tissue. The absence of collagen in the biopsy tissue is another indication that the diagnosis is lymphocytic colitis and not collagenous colitis.

Treatment Of Microscopic Colitis

Some cases of microscopic colitis may resolve on their own, without any specific treatment. For those cases that do require medical intervention, treatment may be initially started with the addition of fiber supplements to the diet. Fiber supplements include psyllium, methylcellulose, or polycarbophil, which can be bought over-the-counter in drugstores. Because the main symptom of microscopic colitis is chronic diarrhea, treatment may also include an anti-diarrheal medication such as loperamide or diphenoxylate.

For more severe cases of microscopic colitis, antibiotics or anti-inflammatory drugs may also be prescribed. Many of the anti-inflammatories used for microscopic colitis are the same as those used to treat IBD: mesalamine, sulfasalazine, and budesonide. Corticosteroids such as prednisone may also be used, to treat microscopic colitis, with the goal of discontinuing their use as soon as symptoms are under control.

Sources:

Crohn’s and Colitis Foundation of America. "Microscopic and ischemic colitis." Crohn’s and Colitis Foundation of America. 22 September 2005. 26 Nov 2006.

Yao, Patrick, MD. "Microscopic Colitis." UCLA Department of Medicine 23 September 2005. UCLA Department of Medicine. 26 Nov 2006.

The National Digestive Diseases Information Clearinghouse. "Collagenous Colitis and Lymphocytic Colitis." The National Digestive Diseases Information Clearinghouse. January 2006. 26 Nov 2006.

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