What is Mastocytosis? Types, Symptoms, and Treatment

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Mastocytosis is a rare disorder and a type of mast cell disease. It is a condition in which there are too many mast cells in the body.

We all have mast cells. They are a type of white blood cell that protect us from certain infections. They also help with healing. But in mastocytosis, there are excess mast cells. When there’s too many mast cells in the skin, bone marrow, digestive system, liver, spleen and/or lymph nodes, it can lead to health problems.

Mastocytosis is often associated with changes to the KIT gene. These changes contribute to uncontrolled mast cell buildup in the body. In adults, the most common change is to the D816V mutation, a tyrosine kinase receptor that is a key feature of mastocytosis. Other changes to this gene may contribute to mastocytosis in children.

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Types of mastocytosis

The two main types of mastocytosis are:

  • Cutaneous mastocytosis – extra mast cells involving only the skin.
  • Systemic mastocytosis – extra mast cells affecting internal organs (including the skin).

Cutaneous mastocytosis

Cutaneous mastocytosis is known as mastocytosis of the skin. It is the most common form of the disease, especially in children. Most people with any type of mastocytosis experience skin symptoms, even when they have systemic disease.

The term cutaneous refers to something that affects the skin. So cutaneous mastocytosis means there is an excess of mast cells in the skin. This can cause skin lesions or growths. It can lead to other cutaneous symptoms such as itchy skin or flushing.

Cutaneous mastocytosis includes the following subtypes:

Urticaria pigmentosa

Urticaria pigmentosa accounts for more than half of all cases of mastocytosis of the skin. Symptoms involve brownish lesions on the skin. The lesions are usually flat, but in some cases they are raised. This has led to a new name for urticaria pigmentosa: maculopapular cutaneous mastocytosis. (A macule is a flat skin lesion and a papule is a raised one.)

Symptoms can be triggered with friction or by scratching. It results in itchy skin with brownish spots, hives, welts or blisters. It can also cause headaches and skin flushing. Severe cases can cause anaphylaxis.

Children who have urticaria pigmentosa often see the condition go into remission during adolescence.

Cutaneous mastocytoma

This is another subtype of mastocytosis of the skin. It accounts for 15-50% of cases only involving the skin. Mastocytoma is a benign (noncancerous) tumor of mast cells that appears in the skin. The tumors are often reddish-brown in color. They can be flat or raised. The tumors may be present at birth or in early infancy. In most cases, there is only one growth, but there can be more.

Diffuse cutaneous mastocytosis

This is the rarest type of mastocytosis of the skin. It occurs in 5-10% of people with cutaneous mastocytosis. Symptoms involve reddened skin that spreads out over the body. Sometimes blisters develop on the skin. Over time, the skin may thicken. It can look like leather or even an orange peel. Diffuse cutaneous mastocytosis is a very rare and severe type of mastocytosis of the skin.

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Systemic mastocytosis

Systemic mastocytosis involves organs and tissues across the whole body. It is more common in adults than children. The symptoms may include (but are not limited to) the skin, digestive tract, liver, spleen and bone marrow. The condition is most common in adults, but some children also develop the condition.

Systemic mastocytosis has several subtypes:

Indolent systemic mastocytosis

This subtype involves the gradual buildup of mast cells in body organs and tissue. Since the buildup occurs slowly, symptoms are mild to moderate and do not usually lead to organ damage. This is the most common form of systemic mastocytosis. It occurs in about 90% of patients. People with the condition can manage it successfully with medication and live a normal life.

Smoldering systemic mastocytosis

This involves a significant increase of mast cells in body organs and tissue, particularly bone marrow, liver and spleen. Symptoms are less severe than other more aggressive subtypes. The condition can transition to more aggressive disease. Regular monitoring can help detect disease progression.

Aggressive systemic mastocytosis

This is a rare and advanced form of systemic mastocytosis. The condition involves the abnormal buildup of mast cells in body organs and tissue. It can lead to organ damage, particularly in the bone marrow, liver or digestive tract, and eventually become life-threatening. Symptoms may include bone problems, weight loss, bloating, or an enlarged spleen or liver. It can progress to mast cell leukemia. There is also a risk for fatal anaphylaxis due to excessive release of histamine and other compounds made by mast cells. It’s important to get symptoms checked early so you have an accurate diagnosis. Then work together with your doctor to develop a management plan. This can improve outcomes.

Systemic mastocytosis with an associated hematologic neoplasm

This rare condition combines the buildup of mast cells in at least one organ system with a cancerous blood disorder.

Mast cell leukemia

This is an extremely rare and severe form of the disease. It involves a large amount of abnormal mast cells found in the blood and bone marrow. This subtype has a poor prognosis. It requires prompt and aggressive treatment by doctors that treat cancer.

Mastocytosis vs. Mast Cell Activation Syndromes (MCAS)

Mastocytosis and mast cell activation syndrome are both disorders involving mast cells. They can cause similar symptoms after the release of mast cell chemical mediators. But these are two distinct conditions.

Mastocytosis is a mast cell disorder that involves the abnormal buildup of mast cells. It occurs in body organs and tissues, such as the skin, bone marrow, heart, respiratory system, liver, spleen and the digestive tract. The buildup leads to symptoms and can progress to serious disease.

MCAS is a condition in which mast cells are overly reactive. They release excessive chemical mediators such as histamine. It is diagnosed when there are severe reactions involving multiple body organs.

It is possible for people to have both mastocytosis and mast cell activation disorders, but this is very rare.

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Symptoms of mastocytosis

Mastocytosis symptoms can vary from person to person. It can depend on the type and severity of the condition.

In cutaneous mastocytosis, the most common symptoms involve the skin. These include spots, flushing of the skin, itchy rashes or lesions.

Systemic mastocytosis can present with more symptoms. Symptoms may involve the skin, bone marrow, liver, spleen, or digestive tract. People with systemic mastocytosis may develop bone pain and fatigue. They may also be at risk for a severe or life-threatening allergic reactions, or anaphylaxis.

Mastocytosis symptoms in adults

Symptoms reflect the body system involved. It may affect a small area of your body (local). It could affect several body systems (systemic). Symptoms may include:

  • Skin: rash or lesions, swelling, flushing
  • Breathing: shortness of breath
  • Stomach: abdominal pain, nausea, vomiting or diarrhea, GERD
  • Throat: swelling
  • Brain: headache, brain fog, memory issues, depression, mood changes
  • Heart: palpitations, blood pressure changes, dizziness, fainting
  • Bones: bone pain, bone density loss, bone fracture (in severe cases)
  • Blood: anemia, bleeding issues
  • Organs: enlarged spleen, liver, or lymph nodes
  • Severe allergic reactions (anaphylaxis)

Mastocytosis symptoms in infants and children

Infants and young children sometimes are unable to tell you what they are feeling. It is often up to parents and other caregivers to watch for symptoms.

Nearly all children with mastocytosis have skin symptoms. What symptoms should parents and caregivers watch for?

  • Skin rash or lesions
  • Skin flushing
  • Raised, red or brown lines or spots on skin when scratched.
  • Colic or reflux
  • Abdominal pain, nausea, vomiting, diarrhea
  • Severe allergic reactions (anaphylaxis)
  • Seizures (this is very rare)

Older children may complain of bone pain, headaches, or fatigue. You may also see changes in their behavior.

Triggers for Mastocytosis Symptoms

Work with your doctor to identify symptom triggers:

  • Temperatures: heat, cold, or sudden weather changes
  • Environment: chemicals, pollution
  • Allergens: pollen, mold, pet dander, dust mites
  • Excessive tiredness or fatigue
  • Exercise
  • Medications: nonsteroidal anti-inflammatory drugs (NSAIDs), antibiotics, some painkillers
  • Contrast dye used in X-rays
  • Venom: insect stings
  • Food and beverages (including alcohol)
  • Infections from viruses, bacteria, or fungus
  • Irritation of skin: pressure, friction, scratching, or vibration

For some people, the trigger is unknown. In this case, work together with your doctor to monitor when symptoms occur.

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Diagnosis and testing

When diagnosing mastocytosis, first the doctor will do a physical exam. The doctor will review your medical history and conduct a series of biopsies and tests.

  • A skin biopsy looks for mast cells in the skin.
  • A bone marrow biopsy and/or a biopsy of other tissues is necessary to diagnose systemic disease.
  • Blood tests look for chemicals called mast cell mediators. These mediators include serum tryptase levels.

Each of these tests aid in the diagnosis and monitoring of the disease.

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Mastocytosis treatment options

There is no cure for mastocytosis. The treatment is based on the severity of the disease and the body organs affected. It focuses on controlling and preventing disease symptoms.

Patients may be treated with medications to block reactivity of the mast cells or the effects of mast cell mediators.

Aggressive forms of mastocytosis, such as mast cell leukemia, require more intense treatment. These include targeted therapies, chemotherapy, or bone marrow transplants.

Here is a list of medications used to treat mastocytosis:

Topical creams, ointments and moisturizers

Topical medications are used most often to treat cutaneous mastocytosis. They can help keep the skin moist. They can also make the skin less prone to physical stimuli. Prescription and over-the-counter options are available.

Antihistamines (H1 blockers)

Antihistamines do as their name suggests – block the effects of histamine released from mast cells. They can help treat skin reactions, including itchy skin and flushing. Antihistamines also can help treat any respiratory or nasal problems caused by the release of histamine.

Antacids (H2 blockers)

These oral treatments can help treat stomach issues caused by mastocytosis. They are often used for heartburn or acid reflux symptoms, including GERD. They can also help with abdominal pain, nausea and vomiting. Newer H2 blockers (ranitidine or famotidine) may be safer in terms of drug interactions.

Mast cell stabilizers

These medications include cromolyn sodium and ketotifen. They treat mast cell activation and slow the release of mediators that cause symptoms. Cromolyn sodium is poorly absorbed from the digestive system into the rest of the body when it is taken orally as a pill. So the medication should be used to primarily treat digestive symptoms.

Epinephrine

People with mastocytosis who are at risk for anaphylaxis need access to epinephrine. Anaphylaxis is a severe allergic reaction. Symptoms may affect multiple body systems, including the skin (itchy hives), digestive tract (swelling of the mouth, tongue or throat, nausea, vomiting, diarrhea), respiratory system (coughing, shortness of breath), and heart (increased heart rate).

Epinephrine is the first line of treatment for anaphylaxis. People at risk for anaphylaxis should carry epinephrine with them at all times. Devices include an epinephrine nasal spray and auto-injector. Two doses are needed in case a second reaction occurs.

If your symptoms improve after one dose of epinephrine and you’re feeling better, you do not need to go the hospital or emergency department. However, you should administer a second dose and seek emergency medical help if…

  • symptoms return or worsen after the first dose of epinephrine;
  • you have severe anaphylaxis;
  • symptoms do not go away promptly or completely after the first dose of epinephrine.

If you do not have epinephrine available, call 911, or go to the hospital, emergency department or urgent care clinic right away for treatment. Do not delay!

Corticosteroids

If symptoms are severe, your doctor may prescribe a short course of oral corticosteroids. These are pills that reduce inflammation.

They should not be taken long-term unless recommended by your doctor. Side effects can be serious, especially if these medications are overused. Side effects may include increase in appetite, weight gain, insomnia, diabetes, thinning skin, bone weakness and mood swings.

Tyrosine kinase inhibitors

Tyrosine kinase inhibitors are designed to help control mast cell disease and stop symptoms before they start. The medications work by blocking the proteins that cause the abnormal buildup of mast cells. Older medications inhibit many tyrosine kinases. Some newer medications can now inhibit only the mutated KIT D816V, which occurs in about 90% of adult systemic mastocytosis patients. These medications effectively turn off mast cells. They can stop or limit histamine release.

Tyrosine kinase inhibitors are taken orally as a pill. They are typically prescribed for people with advanced disease.

  • Avapritinib (Ayvakit®) inhibits KIT D816V and is the only drug that is FDA-approved to treat indolent systemic mastocytosis. It is also used to treat aggressive systemic mastocytosis including mast cell leukemia when KIT D816V is present.
  • Imatinib (Gleevec®) treats indolent and aggressive systemic mastocytosis in people who do not have the KIT D816V mutation.
  • Midostaurin (Rydapt® and Tauritmo®) treats aggressive systemic mastocytosis and mast cell leukemia.

Omalizumab (Xolair®)

Omalizumab is a biologic medication. It is not FDA-approved to treat mastocytosis, however some doctors may prescribe it “off-label.” Omalizumab blocks the protein antibody immunoglobulin E (IgE) from binding to mast cells. It can reduce mast cell reactivity and sensitivity. This can reduce the risk of severe allergic reactions. Omalizumab is typically administered as an injection every 2-4 weeks. The first three injections must be completed at a doctor’s office. Omalizumab is FDA-approved to treat allergic asthma, chronic hives, chronic rhinosinusitis with nasal polyps, and food allergy.

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Mastocytosis is a complex and rare disease. It requires a combination of medical treatment and lifestyle changes. The first step to managing it successfully is to know and avoid your triggers. This will help prevent symptoms.

Once you know your triggers, find ways to avoid them, including those in your environment. Monitor what foods you eat and the medications you take. They may trigger symptoms or interact with medications.

A form of therapy called biofeedback has been shown to help many patients. Biofeedback is a technique that helps patients use their minds to control normally automatic body functions (like breathing or heart rate).

Make sure you have regular medical care. Partner with your doctor to explore all treatment options. This can help you watch for potential problems.

People with mastocytosis may find connecting with support groups helpful. These groups and other resources may provide support and further education.

Questions & Answers (Q&A) on Mastocytosis

Here’s a Q&A with common questions about mastocytosis. If there’s a topic you would like to see addressed here, please email the editor.

In rare cases, systemic mastocytosis can turn into a form of blood cancer. These cases are aggressive forms of the disease and will require immediate treatment.

In most cases, mastocytosis is not deadly. In children, the condition usually affects the skin and often gets better as they grow up. In adults, it can be more serious if it affects multiple body organs.

People with mastocytosis who are at risk for anaphylaxis could face life-threatening symptoms due to a severe allergic reaction. That’s why it is important to keep epinephrine close by for emergency treatment.

Most people with mastocytosis live long and productive lives. Others with the disease may have more serious problems. The outcome depends on how severe the disease is and which organs are affected. Regular check-ups with a doctor are important to manage the condition.

Mastocytosis symptoms may include small, itchy skin lesions. They may appear reddish-brown or yellowish-brown due to the buildup of mast cells and the impact on cells that provide skin color (called melanocytes). These symptoms are often referred to as urticaria pigmentosa, but they are different from hives. (Hives do not typically last more than 24 hours. And when hives go away, the skin usually returns to normal.)

Food is not a common trigger for mastocytosis symptoms. Some people with mastocytosis may still react to certain foods and drinks, particularly alcoholic beverages. The reaction happens through the release of histamine or other chemicals from mast cells after food is ingested.

It is essential to avoid foods that cause a reaction. Some of these foods may include:

  • Aged cheeses
  • Processed meats (such as salami and sausages)
  • Alcoholic beverages (especially wine and beer)
  • Fermented foods (like sauerkraut and kimchi)
  • Certain fish (like tuna, mackerel and sardines)
  • Shellfish
  • Tomatoes
  • Strawberries
  • Pineapples
  • Bananas
  • Nuts

Some people with mastocytosis may also react to spicy foods, vinegar, and certain food dyes.

Keep track of what you eat in a food diary to determine if foods are causing symptoms. Speak with your doctor or a dietitian to get more advice on what to eat and what to avoid.

Yes, there are certain medications some people with mastocytosis should avoid. These medications can trigger mast cells and cause symptoms. They can lead to a severe allergic reaction, or anaphylaxis.

These medications may include (but are not limited to:)

  • Pain relievers such as aspirin, ibuprofen and other NSAIDs
  • Strong pain-relief medications such as morphine or codeine
  • Muscle relaxants and certain anesthetics used during surgery

Patients with mastocytosis should always consult with their doctor before starting any new medication or getting a vaccine to ensure it is safe.

For support and further information about mast cell diseases, please visit The Mast Cell Disease Society.

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