Mastocytosis is a disorder that may occur in both children and adults. It is
caused by the presence of too many mast cells in your body. You can find mast
cells in skin, lymph nodes, internal organs (such as the liver and spleen) and
the linings of the lung, stomach, and intestine. Mast cells play an important
role in helping your immune system defend these tissues from disease. Mast cells
attract other key players of the immune defense system to areas of your body
where they are needed by releasing chemical "alarms" such as histamine and
cytokines.
Mast cells seem to have other roles as well. Found to gather around wounds,
they may play a part in wound healing. For example, the typical itching you feel
around a healing scab may be caused by histamine released by mast cells.
Researchers also think mast cells may have a role in the growth of blood
vessels. No one with too few or no mast cells has ever been found. This fact
indicates to some scientists that having too few mast cells may be incompatible
with life.
The presence of too many mast cells, or mastocytosis, can occur in two forms—cutaneous
and systemic. The most common cutaneous (skin) form is also called urticaria
pigmentosa, which occurs when mast cells infiltrate the skin. Systemic
mastocytosis is caused by mast cells accumulating in the tissues and can affect
organs such as the liver, spleen, bone marrow, and small intestine.
Researchers first described urticaria pigmentosa in 1869. Systemic
mastocytosis was first reported in the scientific literature in 1949. The true
number of cases of either type of mastocytosis remains unknown, but mastocytosis
generally is considered to be an "orphan disease." (Orphan diseases affect
approximately 200,000 or fewer people in the United States.)
Symptoms
Chemicals released by mast cells cause changes in your body’s functioning
that lead to typical allergic responses such as flushing, itching, abdominal
cramping, and even shock. When too many mast cells are in your body, the
additional chemicals can cause
- Musculoskeletal pain
- Abdominal discomfort
- Nausea and vomiting
- Ulcers
- Diarrhea
- Skin lesions
It can also cause episodes of hypotension (very low blood pressure and
faintness) or anaphylaxis (shock).
Diagnosis
Your doctor can diagnose cutaneous mastocytosis by the appearance of
your skin and confirm it by finding an abnormally high number of mast cells on a
skin biopsy. The diagnosis of systemic mastocytosis is made when an
increased number of abnormal mast cells is found during an examination of your
bone marrow.
Other tests that are important in evaluating a suspected case of mastocytosis
include measurement of a protein (tryptase) from mast cells in your blood and a
search for specific genetic mutations that health experts associate with this
disease.
Treatment
Doctors use several medicines to treat mastocytosis symptoms, including
antihistamines (to prevent the effect of mast cell histamine) and
anticholinergics (to relieve intestinal cramping). A number of medicines treat
specific symptoms of mastocytosis.
- Antihistamines frequently treat itching and other skin complaints
- Certain antihistamines work specifically against ulcers; proton pump
inhibitors also relieve ulcer-like symptoms
- Two types of antihistamines treat severe flushing and low blood
pressure before symptoms appear; epinephrine can treat these symptoms
after they begin
- Topical steroids temporarily reduce skin lesions that are
cosmetically disturbing
- Steroids treat malabsorption, or impaired ability to take in
nutrients
In cases in which mastocytosis is malignant, cancerous, or associated with a
blood disorder, steroids and/or chemotherapy may be necessary.
Research
National Institute of Allergy and Infectious Diseases (NIAID) scientists have
studied and treated patients with mastocytosis for more than two decades at the
National Institutes of Health (NIH) Clinical Center.
Some of the most important research advances for this rare disorder include
improved diagnosis of mast cell disease, identification of growth factors that
are responsible for increased mast cell production, and improved treatment. For
example, researchers have developed drugs that help block the action of
chemicals released from mast cells. Researchers are evaluating other drugs that
slow down production of mast cells.
Scientists are also focusing on identifying gene mutations associated with
the disease. Several such mutations have been identified at NIH in a cell
receptor for a mast cell growth factor. Understanding such mutations helps
researchers understand the causes of mastocytosis, improve diagnosis, and
develop better treatment methods.
Source: National Institutes of Health; National Institute of Allergy and Infectious Diseases
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 2/14/2008...#5908
