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Systemic mastocytosis

Medically reviewed by Last updated on Nov 10, 2023.


Systemic mastocytosis (mas-to-sy-TOE-sis) is a rare disorder that results in too many mast cells building up in your body. A mast cell is a type of white blood cell. Mast cells are found in connective tissues throughout your body. Mast cells help your immune system function properly and normally help protect you from disease.

When you have systemic mastocytosis, excess mast cells build up in your skin, bone marrow, digestive tract or other body organs. When triggered, these mast cells release substances that can cause signs and symptoms similar to those of an allergic reaction and, sometimes, severe inflammation that may result in organ damage. Common triggers include alcohol, spicy foods, insect stings and certain medications.


Signs and symptoms of systemic mastocytosis depend on the part of the body affected by excessive mast cells. Too many mast cells can build up in the skin, liver, spleen, bone marrow or intestines. Less commonly, other organs such as the brain, heart or lungs also may be affected.

Signs and symptoms of systemic mastocytosis may include:

The mast cells are triggered to produce substances that cause inflammation and symptoms. People have different triggers, but the most common ones include:

When to see a doctor

Talk to your doctor if you have problems with flushing or hives, or if you have concerns about the signs or symptoms listed above.


Most cases of systemic mastocytosis are caused by a random change (mutation) in the KIT gene. Typically this flaw in the KIT gene is not inherited. Too many mast cells are produced and build up in tissues and body organs, releasing substances such as histamine, leukotrienes and cytokines that cause inflammation and symptoms.


Complications of systemic mastocytosis can include:


To diagnose systemic mastocytosis, your doctor will likely start by reviewing your symptoms and discussing your medical history, including medications you've taken. He or she can then order tests that look for high levels of mast cells or the substances they release. Evaluation of organs affected by the condition also may be done.

Tests may include:

Types of systemic mastocytosis

The five main types of systemic mastocytosis include:

Systemic mastocytosis most commonly occurs in adults. Another type of mastocytosis, cutaneous mastocytosis, typically occurs in children and usually affects only the skin. It generally doesn't progress to systemic mastocytosis.


Treatment may vary, depending on the type of systemic mastocytosis and the body organs affected. Treatment generally includes controlling symptoms, treating the disease and regular monitoring.

Controlling triggers

Identifying and avoiding factors that may trigger your mast cells, such as certain foods, medications or insect stings, can help keep your systemic mastocytosis symptoms under control.


Your doctor may recommend medications to:

A health care professional can teach you how to give yourself an epinephrine injection in the event that you have a severe allergic response when your mast cells are triggered.


If you have aggressive systemic mastocytosis, systemic mastocytosis associated with another blood disorder or mast cell leukemia, you may be treated with chemotherapy medications to reduce the number of mast cells.

Stem cell transplant

For people who have an advanced form of systemic mastocytosis called mast cell leukemia, a stem cell transplant may be an option.

Regular monitoring

Your doctor regularly monitors the status of your condition using blood and urine samples. You may be able to use a special home kit to collect blood and urine samples while you're experiencing symptoms, which gives your doctor a better picture of how systemic mastocytosis affects your body. Regular bone density measurements can monitor you for problems such as osteoporosis.

Lifestyle and home remedies

Systemic mastocytosis can be a complex disease. Understanding your condition is critical to ongoing care and prevention of complications. Ask family or friends if they can help you monitor and care for your condition. Here are some self-care tips:

Coping and support

Caring for a lifelong disorder such as systemic mastocytosis can be stressful and exhausting. Consider these strategies:

Preparing for an appointment

While you may initially consult your family doctor, he or she may refer you to a doctor who specializes in allergy and immunology (allergist) or a doctor who specializes in blood disorders (hematologist).

Preparing and anticipating questions will help you make the most of your time with the doctor. Here's some information to help you get ready for your first appointment.

What you can do

Before your appointment, make a list that includes:

Ask a trusted family member or friend to join you for the appointment. Take someone along who can offer emotional support and help you remember all of the information.

Questions to ask your doctor may include:

What to expect from your doctor

Your doctor may ask questions such as:

Your doctor will ask additional questions based on your responses, symptoms and needs. After getting detailed information about the symptoms and your family's medical history, your doctor may order tests to help with diagnosis and treatment planning.

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