Mastocytosis, NIAID Fact Sheet: NIAID
Article title: Mastocytosis, NIAID Fact Sheet: NIAID
Conditions: Mastocytosis, Systemic mastocytosis, Cutaneous mastocytosis, urticaria pigmentosa
Source: NIAID
January 2002
Mastocytosis
What is mastocytosis?
Mastocytosis is a group of disorders
in both children and adults caused by the presence of too many mast
cells in a person's body. Located in skin, the linings of the
stomach and intestine, as well as other sites, mast cells may play
an important role in helping defend these tissues from disease. By
releasing chemical "alarms" such as histamine, mast cells attract
other key players of the immune defense system to areas of the body
where they are needed.
Mast cells seem to have other roles as
well. Because they gather together around wounds, mast cells 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
been found, which indicates to some scientists that we may not be
able to survive with too few mast cells.
The presence of too
many mast cells, or mastocytosis, can occur in two forms - cutaneous
(skin) and systemic (involves internal body organs). Cutaneous
mastocytosis (CM), the most common form, occurs when mast cells
increase in the skin. It is also called urticaria pigmentosa. CM
mostly affects children.
Systemic mastocytosis is caused
when mast cells collect in the tissues and can affect organs such as
the liver, spleen, lymph nodes, and bone marrow.
Scientists
first described urticaria pigmentosa in 1869. Systemic mastocytosis
was first reported by scientists in 1936. No one is sure how many
people have either type of mastocytosis, but mastocytosis generally
has been considered to be an "orphan disease." (Orphan diseases
affect 200,000 or fewer people in the United States.) Mastocytosis,
however, often may be misdiagnosed, and occur more frequently than
assumed.
What are the symptoms of mastocytosis?
Chemicals released by
mast cells cause changes in the immune system leading to typical
allergy symptoms such as itching, abdominal cramping, and even
anaphylaxis (dangerously low blood pressure).
When too many
mast cells exist in a person's body, the additional chemicals can
cause
- Bone or muscle pain
- Abdominal discomfort
- Nausea and vomiting
- Stomach ulcers
- Diarrhea
- Skin lesions
- Episodes of very low blood pressure and faintness
- Shock
How is mastocytosis diagnosed?
Doctors can diagnose
urticaria pigmentosa by seeing the characteristic lesions which are
dark-brown and fixed. A small skin sample may help confirm the
diagnosis.
By taking a tiny piece of tissue from a different
organ, such as the bone marrow, the doctor can diagnose systemic
mastocytosis. Using special techniques on a bone marrow sample, the
doctor looks for an increase in mast cells. Another sign of this
disorder is high levels of certain mast-cell chemicals and proteins
in a person's blood and sometimes in the urine.
How is mastocytosis treated?
Several medicines help treat
the symptoms of mastocytosis.
- Antihistamines to work against mast cell chemicals
- Medicines to relieve cramping in the intestines
Medicines help treat other signs and symptoms of
mastocytosis, including
- Itching and other skin reactions
- Ulcer-like symptoms
- Low blood pressure
- Inability to take up nutrients from food
In rare cases
in which mastocytosis is cancerous or associated with a blood
disorder, the patient may have to use steroids and/or chemotherapy.
Research
National Institute of Allergy and Infectious
Diseases (NIAID) scientists have been studying and treating patients
with mastocytosis for several years 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 and identification of growth factors and
genetic mechanisms responsible for increased mast cell production.
Researchers are currently evaluating approaches to improve ways to
treat mastocytosis.
Scientists also are focusing on
identifying disease-associated mutations (changes in genes). NIH
scientists have identified some mutations, which may help
researchers understand the causes of mastocytosis, improve
diagnosis, and develop better treatments.
For more information
National Institute of Allergy and
Infectious Diseases
Building 31, Room 7A50, MSC 2520
31 Center
Drive
Bethesda, MD 20892-2520
http://www.niaid.nih.gov/U.S.
National Library of Medicine
8600 Rockville Pike
Bethesda, MD
20894
301-496-6308
http://medlineplus.gov/National
Organization for Rare Disorders
P.O. Box 8923
New Fairfield,
CT 06812-8923
203-746-6518
http://www.rarediseases.org/Mastocytosis
Society, Inc.
433 East 300 South
Spanish Fork, UT
84660
801-798-2032
http://www.mastocytosis.com/NIAID
is a component of the National Institutes of Health (NIH). NIAID
supports basic and applied research to prevent, diagnose, and treat
infectious and immune-mediated illnesses, including HIV/AIDS and
other sexually transmitted diseases, tuberculosis, malaria,
autoimmune disorders, asthma and allergies.
Press releases, fact sheets and other NIAID-related
materials are available on the NIAID Web site at http://www.niaid.nih.gov/.Prepared
by:
Office of Communications and Public Liaison
National
Institute of Allergy and Infectious Diseases
National Institutes
of Health
Bethesda, MD 20892
U.S. Department of Health and
Human Services
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