Mastocytosis happens when mast cells that protect your body from allergens and bacteria mutate (change) and become abnormal cells that set up a continuous allergic response. Mastocytosis symptoms can be mild or severe. Most people can manage symptoms with medication and by avoiding activities and environments that trigger the condition.


What is mastocytosis?

Mastocytosis (pronounced “mas-to-sy-TOE-sis”) is a rare disease that happens when your body makes too many mast cells. Mast cells are white blood cells and part of your immune system. They go to work when intruders like bacteria and allergens threaten your body. Mast cells react to intruders by releasing histamine. This chemical helps cells communicate and triggers your body’s allergic reactions. Mast cells also help produce stomach acid.

You have mast cells throughout your body, mostly in your skin, bone marrow, lungs and the lining of your intestine. Normally, mast cells stop reacting when they’ve taken care of intruders. In mastocytosis, abnormal mast cells multiply and build up in your body. As they multiply, mast cells release more histamine. If you have mastocytosis, your body overreacts to allergens, and you have unusually intense or long-lasting allergic reactions.

Most people can manage mastocytosis symptoms with medication and by avoiding activities and environments that trigger the condition. However, all people with mastocytosis have an increased risk of anaphylaxis. This is a severe allergic reaction that can be life-threatening.

Healthcare providers can’t cure mastocytosis, but they can treat its symptoms and the complications the condition causes.

Types of mastocytosis

There are two types of mastocytosis:

  • Cutaneous mastocytosis: This type typically affects infants and toddlers but may affect adults. In cutaneous mastocytosis, abnormal mast cells build up in your skin and create itchy sores that may be red or dark red, brown or a combination of red and brown.
  • Systemic mastocytosis: This typically affects adults. In systemic mastocytosis, abnormal mast cells build up in your bone marrow, bones, your digestive system and lungs. Abnormal mast cells that build up in your bone marrow may affect blood cell production. Abnormal mast cells that build up in your organs affect how they work. For example, if there are unusually large numbers of mast cells in your stomach, they may produce too much stomach acid and cause ulcers.

Is mastocytosis common?

No, it’s not. Studies vary but estimate that mastocytosis affects 1 in 10,000 to 20,000 people.


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Symptoms and Causes

What are mastocytosis symptoms?

This abnormal growth of mast cells causes a range of symptoms, including:

What age does mastocytosis start?

That depends on the type of mastocytosis. In general, cutaneous mastocytosis may affect children when they’re newborns. Systemic mastocytosis affects adults age 50 and older.

What causes the condition?

Mastocytosis is an acquired genetic disorder, meaning you don’t inherit the condition. It happens when KIT genes mutate (change). KIT genes play a role in developing certain cell types, including blood cells and mast cells. In mastocytosis, mutated KIT genes order mast cells to multiply uncontrollably.

What triggers mastocytosis?

There are dozens of potential mastocytosis triggers and not everyone with mastocytosis reacts the same way. Some activities or experiences that trigger the condition are:

  • Having something touch or rub on your skin so it causes friction.
  • Participating in exercise and physical activity.
  • Being bit or stung by an insect, especially ants, wasps and bees.
  • Drinking beverages containing alcohol.
  • Eating certain foods, particularly spicy foods.
  • Taking certain medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxers and anesthesia.
  • Experiencing sudden changes in temperature, like jumping into very cold water.
  • Having physical or emotional stress.


What are the mastocytosis complications?

Complications include:

  • Osteoporosis, which causes bones to soften and break down.
  • Liver issues, when your liver becomes inflamed and doesn’t work as well as it should.
  • Cytopenia, when your body doesn’t produce enough blood cells.
  • Infections.

Diagnosis and Tests

How is mastocytosis diagnosed?

A healthcare provider will ask about your symptoms and examine your skin. They may order the following tests:

  • Blood tests. Providers may do blood tests to check on the amount of tryptase in your blood. Tryptase is an enzyme that mast cells release when they’re reacting to intruders.
  • Bone scan. Providers may use a bone scan to look for signs of bone damage.
  • Bone marrow biopsy. Providers look for unusual numbers of mast cells in your bone marrow.
  • Genetic tests. If you have systemic mastocytosis, providers may test for mutated KIT genes.


Management and Treatment

What are mastocytosis treatments?

Treatment varies based on mastocytosis type and your symptoms. In general, providers use medications and other treatments to ease symptoms.

Medications for mastocytosis may include:

Providers may use the following treatments:

Treatment complications or side effects

Providers may use a variety of treatments for mastocytosis symptoms. Most treatments have side effects, some more serious than others. If you have mastocytosis, your provider will explain what you can expect, including treatment side effects.


Can mastocytosis be prevented?

No, it can’t. Mastocytosis happens when KIT genes mutate, creating abnormal mast cells that multiply uncontrollably. If you have mastocytosis, you can reduce your risk of allergic reactions by knowing what triggers your allergic reactions.

If certain medications trigger the condition, consider wearing a medical alert bracelet with information that lets other people know what medications you shouldn’t receive.

If you have systemic mastocytosis, you should always carry a self-injecting syringe of epinephrine, a hormone made by adrenal glands. Epinephrine treats severe allergic reactions that could become life-threatening anaphylactic shock.

Outlook / Prognosis

Is mastocytosis curable?

In general, mastocytosis is considered an incurable disease that healthcare providers manage with treatments to ease symptoms and treat complications.

The only potential cure for mastocytosis is an allogeneic stem cell (bone marrow) transplantation. Providers may recommend stem cell transplantation for people who have very aggressive or advanced mastocytosis.

Does mastocytosis get worse over time?

Without treatment, systemic mastocytosis symptoms may get worse over time, as abnormal mast cells affect your bone marrow and organs.

Living With

How do I take care of myself?

Mastocytosis is an incurable disease. Different types of mastocytosis affect people in different ways. If you’re living with mastocytosis, here are some general suggestions that may help:

  • Know what may trigger mastocytosis symptoms. Everyone’s triggers are different.
  • Emotional stress may trigger mastocytosis symptoms. If you need help managing your emotional stress, ask your healthcare provider to recommend programs for managing stress.
  • Wear a medical alert bracelet that lists your condition and medications you shouldn’t take.
  • Always carry a self-injecting syringe of epinephrine to treat severe and life-threatening allergic reactions.

When should I see my healthcare provider?

You’ll have regular checkups with your healthcare provider so they can monitor your symptoms and, if needed, adjust your treatment. Contact your provider any time you notice new symptoms or your symptoms are worse.

When should I go to the emergency room?

You should go to the emergency room if you have extremely strong allergic reactions that aren’t helped with medication.

What questions should I ask my healthcare provider?

If you have this mastocytosis, you may want to ask your healthcare provider the following questions:

  • What type of mastocytosis do I have?
  • What are treatments for the condition type I have?
  • Will treatments make my symptoms go away?
  • What are additional symptoms that may be a sign my condition is getting worse?
  • Will I always need to have treatments?
  • I have a more serious type of this condition. What’s my prognosis?
  • Are there clinical trials I should consider?

A note from Cleveland Clinic

Mastocytosis is a rare condition that happens when your body makes abnormal mast cells that multiply uncontrollably, affecting your skin and organs. Most people with mastocytosis manage its symptoms by knowing what triggers mastocytosis and by taking medication. People with this condition should also have self-injecting syringes of epinephrine at hand to treat severe allergic reactions.

Mastocytosis is an incurable disease. That means you could be living with the condition for a long time. Living with a chronic illness can be challenging. If you have mastocytosis, ask your healthcare provider about programs and services for people with chronic diseases.

Medically Reviewed

Last reviewed on 04/04/2024.

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