What you should know about mast cell diseases

Do you often get a skin rash after you are exposed to an allergen or irritant? Do you also develop breathing problems and stomach issues? Bone or muscle pain? You may want to learn about mast cell diseases. While rare, these diseases are increasingly recognized by doctors. Treatments for these chronic conditions are available.

What are mast cell diseases?

Everyone's symptoms are different. They may include:

Skin: Rashes, swelling, flushing
Stomach: Abdominal pain, nausea, vomiting, diarrhea, heartburn
Brain: Confusion, trouble thinking
Bones: Weak bones/bone pain
Heart: Blood pressure changes, heart racing, fainting
Breathing: Shortness of breath

Mast cell disease can also cause anaphylaxis, a severe or life-threatening allergic reaction. Anaphylaxis occurs from a sudden, rapid release of chemicals from mast cells.

People with mast cell disease may have several triggers causing their symptoms, such as:

• Heat, cold or temperature changes
• Certain foods or medicines
• Alcohol
• Allergens or irritants
• Infections
• Insect stings
• Skin vibration or friction
• Stress
• Exercise
• Contrast dyes during a medical exam

The two main types of mast cell disease are:

Mastocytosis occurs when there is an abnormal buildup of mast cells in the body. This unchecked growth disrupts tissue. Mast cells transfer throughout several body systems, sometimes rapidly.

• People with cutaneous mastocytosis mostly have skin symptoms. This is more common in children.
• People with systemic mastocytosis can have symptoms throughout the whole body and are more at risk for anaphylaxis. The most common type is indolent systemic mastocytosis (ISM). It accounts for up to 90% of adult cases. In ISM, mast cells tend to build up more gradually. Symptoms may start as mild or moderate, but they can worsen over time.

Severe types of mastocytosis are rare, but they can result in organ failure or lead to certain cancers.

Mast cell activation syndrome (MCAS) occurs when overactive mast cells release chemical mediators like histamine too often, with or without a trigger. Symptoms usually affect two or more body systems. People with MCAS are at high risk for anaphylaxis.

A mast cell-related genetic trait called hereditary alpha-tryptasemia (HαT) can affect some people with mast cell disease. People with this trait — about 5% of the population — have high levels of a protein called alpha tryptase. The levels become even more elevated during allergic reactions. People with HαT who also have mastocytosis are at high risk for severe allergic reactions.

How mast cell diseases are diagnosed

Getting an accurate diagnosis can be difficult because mast cell disease symptoms are similar to other conditions. If your symptoms suggest you might have a mast cell disease, consider seeing a specialist. Board-certified allergists can perform tests, such as a skin or bone marrow biopsy or a blood test, to make a correct diagnosis.

Treatment for mast cell diseases

While there's no cure for mast cell diseases, people can manage their symptoms. A treatment plan typically includes medications and avoiding triggers when possible. Medications that can make mast cells less reactive and block effects of mast cell mediators include:

• H1 and H2 antihistamines
• Mast cell stabilizers (cromolyn sodium, ketotifen)
• Leukotriene inhibitors such as montelukast
• Aspirin (under doctor's supervision)
• Omalizumab, a biologic medication
• Tyrosine kinase inhibitors for systemic mastocytosis

Tyrosine kinase inhibitors (TKI) prevent proteins from causing a buildup of mast cells. They can also stop or limit histamine release. TKIs are typically prescribed for people with advanced systemic mastocytosis. One — avapritinib — is also prescribed for indolent systemic mastocytosis.

In rare cases, severe mast cell diseases may be treated with chemotherapy. This does not mean a person with mast cell disease has cancer, but they are at increased risk for certain cancers.

People with mast cell disease who develop anaphylaxis should be treated first — and fast — with epinephrine. Some people may need follow-up care at an emergency department or hospital if symptoms persist.

If you feel you might have mast cell disease, consult your doctor. In honor of International Mastocytosis and Mast Cell Disease Awareness Day on Oct. 20, learn more at AllergyAsthmaNetwork.org or TMSForACure.org.