What Is Mastocytosis?
ArtMarie / Getty Images
Medically reviewed by Jurairat J. Molina, MD
Mastocytosis is a rare disorder that develops when the immune system overproduces mast cells—a type of white blood cell that plays an important role in your body's inflammatory process and helps fight off "foreign invaders," such as bacteria, viruses, or allergens.
When too many mast cells accumulate in one or more parts of your body, they release inflammatory substances like histamine that can trigger a range of symptoms, such as itchy skin, stomach cramping, or bone pain, depending on the location of the mast cell buildup.
Fewer than 50,000 people in the United States live with mastocytosis, which can affect children and adults. Most cases develop due to acquired (not inherited) gene mutations. While there is no cure for this condition, treatments for mastocytosis focus on managing symptoms. Your treatment options may include medications, targeted gene therapies, or stem cell transplantation, depending on the severity and type of mastocytosis you have.
Types of Mastocytosis
There are two main types of mastocytosis: cutaneous and systemic. Healthcare providers diagnose what type you have based on the location of accumulated mast cells.
Cutaneous Mastocytosis
Cutaneous mastocytosis develops when too many mast cells accumulate in the skin. About 90% of people with mastocytosis have this form of the condition, which is more common in children than adults. Most people with cutaneous mastocytosis have only skin-related symptoms such as itching, redness, brown or tan-colored spots that resemble freckles, and hives (raised, itchy bumps on the skin).
Systemic Mastocytosis
Systemic mastocytosis involves mast cell accumulation in the bone marrow and internal organs, such as the gastrointestinal tract, lymph nodes, skin, spleen, or liver. This type is more common in adults and may be indolent (develops slowly) or aggressive (mast cells rapidly build up in the body).
This type of mastocytosis can lead to a wide range of symptoms, such as fatigue, skin flushing (redness and warmth), nausea, headache, abdominal pain, gastroesophageal reflux, nasal congestion, hypotension (low blood pressure), bone pain, and shortness of breath.
Symptoms
Symptoms of mastocytosis may initially be mild but can worsen in severity as mast cells build up in your body. Though symptoms can vary depending on the type of mastocytosis a person has, each type shares common symptoms, including:
Skin flushing (redness and warmth), especially in the face
Itchy and raised hives on the skin
Shortness of breath
Syncope (fainting)
Wheezing
Irritability
Memory problems or difficulty concentrating
Anaphylaxis (severe allergic reactions)
Cutaneous Mastocytosis Symptoms
In addition to the above symptoms, people with cutaneous mastocytosis may experience the following symptoms:
Itchy skin
Red or brown lesions (spots) on the skin
Thickened skin
Blisters on the skin
Nausea and vomiting
Tachycardia (increased heart rate)
Systemic Mastocytosis Symptoms
Systemic mastocytosis may affect multiple organ systems, including the skin, and can cause symptoms such as:
Skin flushing
Nausea
Abdominal pain
Diarrhea
Hypotension (low blood pressure)
Headache
Lightheadedness
Heart palpitations
Bone pain
Memory problems
Trouble focusing
Reddish-brown patches on the skin that may sting or itch
Severe allergic reactions
Causes
Mastocytosis develops when your body produces too many mast cells. Mast cells are an important part of the immune system and help keep you healthy by triggering the body's inflammatory response and stimulating the release of substances that destroy pathogens (harmful cells) like bacteria and viruses. They also play a role in your body's allergy response, stimulating the release of inflammatory chemicals like histamine and tryptase when you're exposed to an allergen.
A gene called KIT controls the growth and replication of mast cells. Mutations in the KIT gene lead to the uncontrolled growth, activation, and build-up of mast cells in your body's tissues. These gene mutations are acquired and occur sometime after conception. This means you do not inherit these mutations and they can't be passed down from generation to generation. What causes these mutations is unknown, but most acquired mutations can occur spontaneously or due to environmental factors such as exposure to chemicals or radiation.
Risk Factors
Mastocytosis is rare, affecting 1 in 10,000 to 20,000 people worldwide. While more research on mastocytosis is needed, experts have established the following two risk factors for the condition:
Age: Cutaneous mastocytosis is most common in infancy and childhood. Systemic mastocytosis is more common in adults, and the risk increases with age.
KIT gene mutations: People with mutations in the KIT gene have an increased risk of mastocytosis.
Diagnosis
Healthcare providers diagnose mastocytosis based on a physical exam and other diagnostic tests. To start, your healthcare provider will ask about your symptoms, including when they started and what triggers or worsens them. If they suspect you have mastocytosis, they will order tests to confirm the diagnosis. These tests may include:
Skin biopsy: A procedure that removes a small sample of the affected skin and sends the sample to the lab, where a pathologist examines it under a microscope to check for the presence of mast cells.
Bone marrow biopsy and aspiration: This test involves removing small samples of bone marrow fluid and tissue and sending them to the lab to look for excess mast cells. The procedure uses a needle to remove the tissue and fluid samples from your pelvic bone.
Blood tests: These exams look for high levels of tryptase in the blood—a type of enzyme that is often elevated in people with mastocytosis. Blood tests can also show how well your internal organs are functioning.
Urine tests: This common test helps look for high levels of histamine and other substances released by mast cells in your urine, which is common in people with mastocytosis.
Genetic testing: Your healthcare provider may recommend genetic testing, which involves testing a blood sample to look for gene mutations on the KIT gene, specifically the KIT D816V mutation, which is the most common mutation associated with mastocytosis.
Treatment
There is no cure for mastocytosis, so treatment focuses on controlling symptoms. Depending on the type and severity of mastocytosis, your treatment plan may include medications, targeted therapies, or stem cell transplantation.
Medications
Your healthcare provider may prescribe medications to help manage symptoms or reduce and control mast cell activity. These medications may include:
Antihistamines: Medications such as Zyrtec (cetirizine), Pepcid (famotidine), and Benadryl (diphenhydramine) block histamine, which is a chemical that mast cells release. These medicines help relieve allergy-like symptoms such as itching, flushing, and hives.
Corticosteroids: Topical steroid creams applied directly to the affected area can relieve skin-related symptoms, such as itching and redness.
Mast cell stabilizers: Gastrocrom (cromolyn sodium) is a mast cell stabilizer that prevents mast cells from releasing histamines and other inflammatory substances. Taking this medication can reduce gastrointestinal symptoms (e.g., diarrhea, abdominal pain) and skin symptoms (e.g., itchiness, flushing).
Epinephrine: People with mastocytosis have an increased risk of severe allergic reactions (anaphylaxis) and should carry an Epi-pen (epinephrine) with them at all times in the event of a severe allergic reaction.
Targeted Therapies
Targeted therapies block the growth of mast cells by inhibiting the actions of kinase enzymes—which are enzymes that play a role in the growth, division, and signaling of mast cells. These therapies generally have fewer side effects than systemic medications because they target specific enzymes and limit damage to other cells.
Targeted therapies for mastocytosis include:
Ayvakit (avapritinib): An oral medication prescribed to people with systemic mastocytosis associated with the KIT D816V gene mutation
Gleevec (imatinib mesylate): An oral medication prescribed to people with mastocytosis who do not have the KIT D816V gene mutation
Rydapt (midostaurin): An oral medication that slows or prevents the growth of abnormal mast cells
Stem Cell Transplant
Stem cell (bone marrow) transplantation is a treatment option for people with advanced and aggressive forms of systemic mastocytosis. People who undergo stem cell transplantation must first go through chemotherapy or radiation therapy to destroy all unhealthy cells in the bone marrow, blood, and other body parts before the transplant takes place.
There are two types of stem cell transplantation for mastocytosis:
Allogenic (ALLO): Involves using stem cells from a matched donor with genetics compatible with the recipient
Autologous (AUTO): Involves collecting, treating, and reintroducing your stem cells into your body
Although stem cell transplantation offers a potential cure for some people with advanced mastocytosis, it is an intense and complex process that involves significant risks—such as serious infections. Keep in mind: this is not an ideal treatment for most people.
How to Prevent Mastocytosis
Unfortunately, there is no known way to prevent mastocytosis since gene mutations associated with the condition often develop spontaneously. For people with mastocytosis, the best way to reduce the severity of your symptoms is to identify and avoid anything that might trigger mast cell activation and histamine release.
Triggers vary from person to person and may include:
Extreme temperatures
Certain medications (e.g., non-steroidal anti-inflammatory drugs)
Alcohol
Allergens (e.g., dust, pollen, insect bites)
Related Conditions
Because mast cells are part of the immune system and play an important role in the body's inflammatory response, people with mastocytosis are more likely to have or develop other related conditions, which include:
Mast cell activation syndrome: A condition that occurs when mast cells frequently release inflammatory chemicals and cause severe allergic reactions
Hereditary alpha-tryptasemia: A genetic trait that causes mast cells to produce elevated levels of tryptase protein, which prompts the release of histamine and increases the risk of severe allergic reactions
Osteoporosis: The accumulation of mast cells in your bone marrow can disrupt bone formation, which can weaken your bones and increase the risk of fractures
Living With Mastocytosis
Between managing symptoms and avoiding triggers, living with mastocytosis can have a significant effect on your day-to-day life. Sometimes, you may feel overwhelmed, but it's important to remember that managing the condition with proper treatment and support is possible.
Cutaneous mastocytosis, especially in children, often resolves on its own over time. Systemic mastocytosis can be more challenging and increases the risk of severe, life-threatening allergic reactions (anaphylaxis). Avoiding triggers and following your treatment plan can help manage the condition. It may also help to work closely with your healthcare provider to manage the effects of the condition on your overall quality of life.
Frequently Asked Questions
What is the life expectancy of someone with mastocytosis?
The life expectancy of someone with mastocytosis varies, depending on the type and severity of the condition. Cutaneous mastocytosis in children usually resolves over time, and adults with this form can expect an average life expectancy. People with milder forms of systemic mastocytosis generally have an average life expectancy, but more aggressive forms of the condition may reduce life expectancy.
Can mastocytosis be cured?
There is no cure for mastocytosis, but treatments can manage symptoms and improve your quality of life.
At what age is mastocytosis common?
Cutaneous mastocytosis is most common in infants and children, and systemic mastocytosis is more common in adults. With systemic mastocytosis, the risk of developing the condition increases with age.
For more Health.com news, make sure to sign up for our newsletter!
Read the original article on Health.com.
