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Systemic Mastocytosis


Systemic mastocytosis is a disorder where mast cells are abnormally increased in multiple organs including the bone marrow. Mast cells are immune cells that produce a variety of mediators, such as histamine, that are important in the body’s allergic responses.

When mast cells are present in greatly increased numbers, the amount of released mediators can be very high and thereby cause multiple symptoms. The disease can occur in both children and in adults.

Symptoms & Diagnosis

Initial signs of this disease may include “spots” that look like freckles on the skin of a person' inner thighs or stomach. These spots are called urticaria pigmentosa and can transform into hives and itch if stroked or irritated, or if the skin is exposed to sudden changes in temperature such as a hot shower.

Other common symptoms include the following:
•    Anaphylaxis
•    Shortness of breath
•    Low blood pressure
•    Hives and swelling
•    Itching
•    Nausea and vomiting
•    Diarrhea
•    Fainting
•    Headache
•    Uterine cramps/bleeding
•    Flushing
•    Musculoskeletal pain

Diagnosis can include the following studies and should be conducted by a physician with special knowledge of this disorder:
•    Skin and bone marrow biopsies
•    Measurement of mast cell mediators in blood and urine
•    Blood count
•    Liver function studies
•    Genetic tests

Video: What are Mast Cell Disorders and Mastocytosis?

Treatment & Management

The objective of treatment is to control the effects of mast cell released mediators by avoidance of dietary and environmental triggers as well as the use of various medications. Antihistamines are commonly used. Cromolyn sodium, ketotifen and leukotriene-modifying agents are additional medications which may provide benefit. Epinephrine may be required to treat episodes of low blood pressure. More aggressive forms of Systemic Mastocytosis may require interferon, immune modulators or chemotherapeutic agents.

Find out more about Mast Cell Activation Syndrome (MCAS).


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