Thursday, March 20, 2014

What do mast cells look like under the microscope in mastocytic enterocolitis?

Mast cells are normally present in the lining of the intestinal tract (and in other tissues throughout the body) where they provide defense against infection. Mast cells contain a variety of chemical mediators for infection fighting that include histamine, leukotrienes, interleukin, eosinophilic chemotactic factor and many others. These are released in response to a threat. For example should you contract food poisoning eating potato salad at the church picnic, swallow lake or stream water containing giardia parasite, or get exposed to the norovirus on your vacation cruise, mast cells residing in your digestive tract lining respond by releasing a variety of chemical mediators to kill the infectious organism and purge you body of it as well. The results are symptoms of acute nausea, vomiting and diarrhea. However, in some individuals, especially women who have been diagnosed with diarrhea predominant irritable bowel syndrome (IBS), excess numbers of mast cells migrate to and stay just under the surface lining of the digestive tract. Once there they can be triggered by stress, mechanical processes of digestion and/or ingestion of variety of foods and food additives to release their mediators resulting in digestive symptoms. However, knowing that there are increased numbers of mast cells in your intestinal lining requires 1) you have biopsies done of the intestine during upper and/or lower scope procedures (EGD and/or colonoscopy) and 2) the pathologist perform special stains (mast cell immunohistochemistry tryptase) stains on the biopies. If both are done the pathologist will be able to see mast cells and count them. If they number 20 or more per high power field then that meets criteria for a condition called mastocytic enterocolitis or mastocytic inflammatory bowel disease. See the photo that shows what mast cells look like on biopsies where special mast cells stains were performed though visually the surface of the bowel looked normal on scope procedure and standard biopsy stains were also normal. .

2 comments:

AKLAP said...

Can or will the mast cell count ever return to normal?

Thanks!

Al

Dr Scot Lewey said...

Al,

They can and do return to normal. Mast cell numbers are known to fluctuate. However, persistent elevations seem in my and Dr. Phil Miner's experience be associated with persistent and ongoing symptoms. Treatment with combination therapy of type 1 and type antihistamines (for example Zyrtec and Zantac) plus a mast cell stabilizing medication has in my experience improved symptoms and normalized mast cell number in many patients. Gastrocrom/cromolyn sodium and Ketotifen are the two mast cell stabilizers available in US, the former in a brand form that is liquid. The latter needs to be specially formulated in US. I find that ketotifen is both better tolerated and more effective in my experience. Four to six months therapy is recommended. When I have had the opportunity to re-biopsied individuals after treatment, in general those without or with minimal symptoms have normalized their mast cell numbers whereas in general those who are still having symptoms usually still have increased mast cells. A few patients I have had normalize their mast cells and become symptom free, then later have recurrent symptoms and increase mast cells are found again. Some celiac patients with recurrent or persistent GI symptoms who are in remission for celiac on a gluten free diet (biopsy and blood tests are normal) I have found have elevated mast cells and respond favorably to treatment for excess mast cells.

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