Systemic mastocytosis is a rare blood disorder. It happens when your body makes abnormal mast cells that multiply. Mast cells defend against intruders such as allergens. In systemic mastocytosis, abnormal mast cells set up a continuous allergic response. The cells also multiply uncontrollably, affecting your skin and internal organs.
Systemic mastocytosis is a rare blood disorder. It happens when your body makes abnormal mast cells. Mast cells are white blood cells and part of your immune system. They’re first responders when allergens and other intruders attack your body. In systemic mastocytosis, abnormal mast cells multiply, setting up a continuous allergic response that may affect your skin and internal organs.
Healthcare providers can’t cure systemic mastocytosis, but they can treat symptoms and complications the condition causes. Most people with systemic mastocytosis have mild symptoms they can manage with medication and by avoiding activities that trigger the condition. Rarely, systemic mastocytosis symptoms get worse or become cancer. All people with this condition have an increased risk of anaphylaxis. This is a severe allergic reaction that can be life-threatening.
You have mast cells throughout your body, mostly in your skin, lungs and the lining of your intestine. Mast cells protect your body from intruders such as bacteria and allergens. Mast cells also help produce stomach acid.
When mast cells detect intruders, they release histamine. Histamine sets off an inflammatory (allergic) response. At the same time, small sacs within each mast cell called mediators release substances to defend against intruders.
Normally, mast cells and mediators stop their work after dealing with intruders. In systemic mastocytosis, you have large numbers of abnormal mast cells continually releasing histamine and other substances. This chemical overload can cause a range of issues.
For example, abnormal mast cells that build up in your bone marrow may affect blood cell production. Likewise, unusually large numbers of mast cells affect organ function. For example, if there are unusually large numbers of mast cells in your stomach, they may produce too much stomach acid and cause ulcers.
Systemic mastocytosis typically affects adults. Another type of mastocytosis — cutaneous mastocytosis — typically affects children.
There are six systemic mastocytosis types. Each type may affect you in different ways. In general, the more abnormal mast cells you have, the greater the chance you’ll have serious health issues. Systemic mastocytosis types include:
It can be. While most people don’t have severe types of systemic mastocytosis, they do have an increased risk of anaphylaxis. Some people may go into anaphylactic shock, which is life-threatening.
Systemic mastocytosis isn’t common. A 2018 population analysis concluded that 1 in 10,000 people in the U.S. has the condition.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Systemic mastocytosis symptoms vary depending on where the abnormal mast cells gather. For example, someone who has too many mast cells in their stomach may develop ulcers and have symptoms including belly pain. Common systemic mastocytosis symptoms include:
People with systemic mastocytosis may suddenly develop several symptoms that come on at the same time and then go away. Healthcare providers may refer to this as a mastocytosis attack.
Many of these symptoms are similar to symptoms of other less serious illnesses. Having these symptoms doesn’t mean you have systemic mastocytosis. But if you have several of these symptoms at the same time and the symptoms keep happening, talk to a healthcare provider. They’ll evaluate your situation and determine what’s causing your symptoms.
Research shows about 80% of people with this condition have a mutated KIT gene. KIT genes play a role in developing certain cell types, including blood cells and mast cells. The mutation happens after conception and isn’t hereditary.
Many things may trigger systemic mastocytosis. Not everyone with the condition reacts to the same triggers. If you have this condition, ask your healthcare provider what triggers you should avoid. Some common triggers include:
Providers may do the following tests to diagnose this condition:
Healthcare providers treat systemic mastocytosis by managing symptoms and complications. For example, they may prescribe H-2 blockers (antacids) to reduce symptoms caused by excess stomach acid. If systemic mastocytosis causes anemia, providers will treat the anemia. Treatments for symptoms may include:
Systemic mastocytosis happens when a certain gene mutates soon after conception. That means you can’t prevent it. You can prevent systemic mastocytosis attacks by avoiding spicy foods and alcohol, certain medications and activities that trigger attacks.
Triggers vary from person to person, so you should ask your healthcare provider what triggers you should avoid. 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 your adrenal glands. Epinephrine treats severe allergic reactions that could become life-threatening anaphylactic shock.
Systemic mastocytosis is considered an incurable disease. But healthcare providers have treatment strategies to manage symptoms and complications. Rarely, bone marrow transplantation may cure systemic mastocytosis. But this treatment is typically only available to a limited number of people who have a very advanced or aggressive form of systemic mastocytosis.
That depends on the condition type. Typically, people with indolent systemic mastocytosis manage the condition with treatment and by avoiding triggers. They have a typical life expectancy. People with more aggressive condition types typically die a few years after diagnosis.
Self-care is a big part of living with the most common type of systemic mastocytosis. If you have this condition, you should:
If you have systemic mastocytosis, your healthcare provider will monitor your treatment and symptoms with regular checkups. Contact your provider any time you notice new symptoms or your symptoms are worse.
Most people with systemic mastocytosis are able to manage symptoms. But you should go to the emergency room if your symptoms suddenly get worse.
Systemic mastocytosis is a rare illness. If you have this condition, you may want to ask your healthcare provider the following questions:
A note from Cleveland Clinic
Systemic mastocytosis is a rare blood disorder. It happens when your body makes abnormal mast cells that multiply, affecting your organs. Most of the time, people can manage systemic mastocytosis with medication and lifestyle changes. But this condition increases the risk of life-threatening anaphylactic shock, a very severe allergic reaction. People with systemic mastocytosis should have self-injecting syringes of epinephrine at hand to treat severe allergic reactions.
Last reviewed by a Cleveland Clinic medical professional on 10/28/2022.
Learn more about our editorial process.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy