Collagenous Colitis and Lymphocytic Colitis
Collagenous colitis and lymphocytic colitis are chronic diseases in which certain kinds of white blood cells infiltrate the lining of the large intestine, leading to watery diarrhea.
These chronic diseases can affect the entire length of the large intestine, including the sigmoid colon and the rectum, but often in a patchy distribution. The lining of the intestine develops a thicker layer of a type of connective tissue (collagen) or an accumulation of lymphocytes (a certain type of white blood cell).
The cause is unknown, although an overactive immune response to some unidentified triggering factor seems possible. Many people who develop collagenous colitis or lymphocytic colitis have been regular users of nonsteroidal anti-inflammatory drugs (NSAIDs), but these drugs have not been proven to be a cause of the diseases. Unlike Crohn's disease and ulcerative colitis, collagenous colitis and lymphocytic colitis do not increase the risk of colon cancer.
Collagenous colitis develops primarily in middle-aged or older women; lymphocytic colitis may develop in younger people and occurs in both sexes equally.
Symptoms and Diagnosis
In addition to nonbloody, watery diarrhea, people with collagenous colitis or lymphocytic colitis often experience crampy abdominal pain, nausea, abdominal expansion (distention), and weight loss. Fasting for a few days often leads to a decrease in the frequency and amount of diarrhea. Diarrhea and other symptoms often fluctuate, with periods of worsening symptoms and periods of improvement or complete resolution.
A doctor considers the diagnosis of collagenous colitis or lymphocytic colitis when a person has persistent watery diarrhea and when tests do not reveal another cause. The diseases are diagnosed by microscopic examination of several samples of tissue taken from the lining of the large intestine obtained during colonoscopy (examination of the large intestine with a flexible viewing tube).
Treatment
Antidiarrheal drugs, such as anticholinergic drugs or small doses of loperamide or diphenoxylate, are effective for many people with these diseases. Anti-inflammatory drugs, such as salicylates (for example, bismuth subsalicylate), sulfasalazine, and mesalamine, are effective as well. Antibiotics such as metronidazole and erythromycin also seem to help, although infection has not been found to be a cause of the diseases. Corticosteroids (such as prednisone) also work well but are usually reserved for people who do not respond to other drug treatment.
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