Collagenous colitis and lymphocytic colitis
Collagenous colitis is a chronic inflammatory disease in which white blood cells of a certain type infiltrate the lining of the large bowel, causing severe inflammation and thickening of the wall, and resulting in watery diarrhea. Lymphocytic colitis is another inflammatory condition similar to collagenous colitis.
The disease is not limited to any specific area of the large intestine and can affect the whole length of it, including the last part called sigmoid colon, as well as the rectum. Often the diseased areas are not continuous, but occur intermittently along the large bowel. A type of WBC called lymphocytes may accumulate in the walls in large numbers. A connective tissue called collagen develops as a thick layer on the lining of the large bowel making it less absorbent of fluids resulting in watery stools.
The exact reason for the development of these diseases is not known. Excessive reaction of the immune system to dietary or environmental triggers is thought to be resulting in the inflammation of the intestinal lining. These diseases are more frequently found in people who use non-steroidal anti-inflammatory drugs regularly, but there is no conclusive proof of the role of NSAIDs in causing them. Neither collagenous colitis nor lymphocytic colitis elevates colon cancer risk, unlike the other chronic inflammatory diseases like ulcerative colitis and Crohn’s disease.
The incidence of collagenous colitis is higher in women, especially among those who are middle aged and older. However, irrespective of age, both men and women are equally prone to developing lymphocytic colitis.
Symptoms and Diagnosis
Thin watery diarrhea is the most common symptom associated with both collagenous colitis as well as lymphocytic colitis. However, the diarrhea is not bloody, unlike other inflammatory diseases of the bowel such as ulcerative colitis and Crohn’s disease. Other symptoms include nausea, distention of abdomen, pain, and abdominal cramps. Loss of appetite and weight loss are also common. A few days of fasting has a beneficial effect of alleviating symptoms. The symptoms appear during flare ups, with periods of remission in between.
Chronic watery diarrhea without bloody stools may alert the doctor to the possibility of these two inflammatory bowel diseases, especially when other causes are not detected. These two inflammatory conditions are together known as microscopic colitis, because a microscopic analysis of a tissue sample of the lining of the large bowel is the diagnostic test for both collagenous colitis as well as lymphocytic colitis. A colonoscopy is conducted to view the interiors of the large intestine and to obtain a tissue sample of the lining.
Treatment
Drug therapy includes treating the diarrhea with diphenoxylate and loperamide which are antidiarrheal drugs having anticholinergic effect. Mesalamine and sulfasalazine are immonomodulating drugs used for their anti-inflammatory effect. Bismuth subsalicylate is another useful drug to relieve inflammation. Antibiotics, and another drug called cholestyramine which can bind to bile salts, are also used for the treatment.
Prednisone is a corticosteroid which is very effective in the treatment of inflammatory bowel diseases, but it is used only when other drug therapies are not effective because of the potential ill effects of long-term corticosteroid use. Another corticosteroid called Budesonide which has lesser side effects may be tried.
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Yasser Elnahas

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