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Life can be complicated, unpredictable and even painful when your body’s always in defense mode.

From aggravating skin rashes to dangerous allergic reactions (anaphylaxis), systemic mastocytosis (SM) keeps your immune system on high alert. This rare, complex blood disorder affects cells in your immune system called mast cells. Mast cells protect your body against intruders like allergens and bacteria by releasing histamine. If you have SM, your mast cells don’t stop releasing histamine even after they respond to the intruder. Instead, they multiply quickly, build up in your body and keep releasing histamine. This can cause your immune system to become hypersensitive to a lot of different allergens and may even damage your organs.

Having a team of experienced healthcare providers on your side is a good first step in getting things under control. Cleveland Clinic connects you with providers from many specialties who all have one goal — working together to provide you with the most personalized care and support.

Why Choose Cleveland Clinic for Systemic Mastocytosis Care?

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Recognized expertise:

People come to Cleveland Clinic from all over the U.S. for rare blood disorder treatment they can’t find elsewhere. And providers regularly refer their patients with highly challenging conditions like advanced SM to us for treatment.

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Personalized care:

Mast cell disorders affect everyone differently. Treatment will work best when you have a care plan tailored to your unique needs and symptoms. We connect you with the right providers and therapies to give you the best results — physically, mentally and emotionally. Meet our team.

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Comprehensive treatment:

There are several types of systemic mastocytosis. And each affects different organs. Whether you’re having problems with your skin, bones, liver, spleen, lymph nodes or gastrointestinal (GI) tract, we have experts who can help.

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Virtual visits:

Not all appointments need to be in person. Virtual visits let you meet one-on-one with your providers using your internet connection and a smartphone, tablet or computer.

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National recognition:

Cleveland Clinic is a trusted healthcare leader. We're recognized in the U.S. and throughout the world for our expertise and care.

Understanding Systemic Mastocytosis

Everyone has mast cells, a kind of immune cell that plays an important role in your body’s defense mechanism. Think of them as first responders. They spring to action when allergens and other invaders attack your body. They multiply and get to work — creating something called histamine to trigger an allergic response.

Sometimes, though, these cells multiply even when there are no intruders. This can set off a constant allergic response (too many histamines all the time) that can affect your skin, bone marrow and internal organs. You can get rashes, bone pain, headaches, heart palpitations, itching, fatigue, bruising and stomach ulcers. You could also have mood swings and depression. Symptoms can come and go suddenly (mastocytosis attacks).

Types of systemic mastocytosis

There are six types of systemic mastocytosis:

  • Indolent systemic mastocytosis: The most common one, it typically progresses very slowly and doesn’t affect your organs.
  • Systemic smoldering mastocytosis: This affects your liver, spleen and lymph nodes.
  • Systemic mastocytosis with hematologic neoplasm: It can be present with a second blood cancer, like myelodysplastic syndrome.
  • Aggressive systemic mastocytosis: This happens when too many mast cells in your bone marrow make it hard for the bone marrow to make blood cells. Low numbers of blood cells can affect your liver, spleen, digestive tract and cause weak or broken bones (fractures) and bone lesions.
  • Mast cell leukemia or sarcoma: The least common, but most severe, type.
  • Mast cell sarcoma: Rarely, tumors can grow from abnormal mast cells in your body’s tissues.

Diagnosing Systemic Mastocytosis at Cleveland Clinic

Not only are there many types of systemic mastocytosis, but its symptoms are similar to those of other conditions. So, it can easily be confused with other things.

Our mastocytosis experts follow the latest National Comprehensive Cancer Network® guidelines when making a diagnosis. These guidelines help us more accurately figure out what kind of SM you have, if it’s cancerous and how bad it is (its stage).

What to expect at your first visit

When you come to Cleveland Clinic for your first visit, we’ll want to hear all about what’s going on with you — from the first time you noticed symptoms to how they affect your life.

This information helps us pinpoint what’s going on and craft a highly individualized treatment plan focused not just on your test results and diagnosis, but also on your unique needs and goals.

You can expect to have a physical exam so we can check out your symptoms and look for signs of SM. We’ll also order some tests to help further confirm our diagnosis:

Blood tests

Blood tests can measure a blood enzyme (tryptase) that mast cells make to help fight invaders. High levels of this enzyme could point to systemic mastocytosis. We’ll do a complete blood count (CBC) to measure:

We’ll also run tests to see how well your organs work, including your liver, spleen and kidneys.


We may do a skin biopsy, bone marrow biopsy or organ biopsy to see if you have really high numbers of mast cells. A pathologist (cell and tissue specialist) will examine a small sample of skin or bone marrow under a microscope to look for abnormal mast cells.

Imaging exams

We may use imaging exams to get a closer look at your bones, liver, spleen and digestive organs. These can include:

Genetic testing

Systemic mastocytosis is usually linked to an abnormal gene called KIT. We can do genetic testing to find out if you have the mutation (change in a gene that makes it abnormal). You aren’t born with the mutation. It can happen at any time after birth. So, having the abnormal gene doesn’t mean you’ll pass on the condition to your children.

Meet Our Systemic Mastocytosis Team

If you choose Cleveland Clinic, you’ll benefit from our team-based approach to care. We carefully choose providers from different specialties for your healthcare team — and all will have experience in treating uncommon blood conditions like SM. Your team will depend on the type of SM you have, your symptoms and your needs. It could include:

These providers (and possibly others) work together to confirm a diagnosis and build the right treatment plan for your needs, health and goals.


Our healthcare providers see patients in Northeast Ohio.

Treating Systemic Mastocytosis at Cleveland Clinic

Treatment for systemic mastocytosis depends on how it’s affecting you and your health. Your care team works with you to customize a treatment plan aimed at helping you manage symptoms and prevent serious complications — like anaphylaxis or anemia.

To do this, our systemic mastocytosis specialists may recommend treatments like:

Taking the Next Step

When you have systemic mastocytosis, your allergy response kicks into overdrive and decides to fight you. All day and night. This can leave you feeling itchy, sick, exhausted and even lead to internal organ damage. Cleveland Clinic’s experienced providers can help. We’ll work with you to craft a personalized treatment plan that will help you manage your SM symptoms and get you the relief you need.

Getting an appointment with Cleveland Clinic’s systemic mastocytosis experts is easy. We’ll help you get the care you need.


Getting an appointment with Cleveland Clinic’s systemic mastocytosis experts is easy. We’ll help you get the care you need.

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