Mastocytic enterocolitis (MCE) is a new disorder, still not known to many doctors or patients,
that is often an unrecognized cause of many digestive symptoms, most commonly abdominal
pain and diarrhea. However, it can cause other digestive and non-digestive symptoms and
sometimes it is associated with constipation. It is now known that MCE is a cause of diarrhea
predominant Irritable Bowel Syndrome (IBS). It may be a subtype of IBS or it's own form of
microscopic inflammatory bowel disease (IBD). 

Mastocytic enterocolitis is diagnosed by the presence of increased mast cells (more than 20
per high power field under the microscope) in intestinal biopsies. The surface lining of the
intestine in this condition almost always looks completely normal so to detect this disorder
biopsies have to be done by the doctor even when the intestine looks normal. Furthermore,
mast cells cannot be readily seen or counted using the standard stains done on intestinal
biopsies. To be detected, MCE requires that the doctor performing the scope procedure
and/or the pathologist reviewing the biopsy slides have suspicion of the condition or that
they routinely perform special stains (tryptase immunohistochemistry stains) that these cells
stain with and bring them to light so that they are easy to see and count. 

The term enterocolitis comes from the combination of the terms "entero" for small intestine
and colitis. Colitis is comes from colon, shortened to "col", combined with the suffix "-itis"
meaning "inflammation of".  Enteritis, inflammation of the small intestine alone, comes from
"entero" shortened to "enter" combined with "itis".

Mast cells contain numerous granules or packets of chemicals.  These granules contain a
variety of chemicals that regulate or mediate body reactions. These chemicals in mast cells
therefore are known as chemical mediators. Histamine is one of the main chemical mediators
in mast cells. Histamine is released in great amounts when mast cells are stimulated or
triggered. Other chemicals include interferon, interleukin, leukotrienes, and eosinophilic
chemotactic factor.