The above slide is of colon tissue retrieved by biopsy during colonoscopy. The surface lining was normal in appearance but the patient had severe chronic diarrhea. The image shows too many purplish dots which are lymphocytes up along the intestinal lining surface.

Biopsies of normal appearing colon lining is required to diagnose microscopic colitides (microscopic forms of colon inflammation or colitis) that cause diarrhea. These conditions are often misdiagnosed as irritable bowel syndrome (IBS) because either a colonoscopy is not done; or is done and appears normal but no biopsy is performed. 

The most commonly diagnosed forms are lymphocytic colitis and collagenous colitis. However, a third form, mastocytic enterocoliltis is more common but usually not diagnosed not only because of failure to biopsy normal appearing colon lining but failure to request a special stain, mast cell tryptase immunhistochemistry stains on normal biopsies. You can read more about mastocytic enterocolitis on the separate webpage dedicated to this increasingly recognized mimic of or possiby subtype of IBS. 

The above photo shows microscopic findings in collagenous colitis. The increased pink material under the surface of the lining is collagen. This increased collagen constitutes collagenous colitis. This is a microscopic form of colitis that causes diarrhea. It is of unknown cause. It affects men and women equally but like lymphocytic colitis is more commonly in patients in their 50's, 60's or 70's. It can be more difficult to treat than lymphocytic colitis. It also may be related to gluten sensitivity and some patients have a variant of celiac called collagenous sprue. Treatment with medication is the same as of lymphocytic colitis.

Lymphocytic colitis is a condition of increased white blood cells called lymphocytes in the lining of the large intestine or colon. It is more common in women but affects both men and women. It is commonly linked to sensitivity to gluten. It is usually treated with an anti-inflammatory medication for the large bowel such as a 5-ASA type medication like those used in ulcerative colitis and Crohn's disease and/or a steroid. Prednisone often works well but side effects of longterm prednisone limit it's use whereas budesonide/enterocort, a modified steroid with little absorption into the blood stream, therefore few side effects is a excellent treatment option. For those who are sensitive to gluten or wheat, a gluten free diet often helps.

Dr. Scot Lewey is the Food Doc. He is a physician specializing in food allergy, intolerance and sensitivity. His interests expanded after his personal and family experiences with allergies, celiac disease, gluten and dairy sensitivity.