Mastocytosis is a genetic immune disorder in which certain cells (mast cells) grow abnormally and cause a range of symptoms, including diarrhea and bone pain. You can't prevent it, but you can avoid triggers and get treatment.
Mastocytosis is a condition where certain immune cells, called mast cells, build up under the skin and/or in the bones, intestines and other organs.
This abnormal growth of mast cells causes a range of symptoms, including itchy bumps on the skin, gastrointestinal (GI) issues such as diarrhea, and bone pain. It can increase the risk of anaphylaxis (a severe allergic response) when patients come across certain environmental triggers (such as a bee sting). In some cases, the mastocytosis can be aggressive and lead to death if left untreated. Mastocytosis is not contagious.
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Mast cells are type of white blood cells located all over your body. People have the highest numbers of mast cells where the body meets the environment: the skin, lungs and intestinal tract.
Normally, mast cells are part of your immune system. When mast cells detect a germ or virus, they set off an inflammatory (allergic) response by releasing a chemical called histamine. This response protects your body from germs and infections.
Mast cells are also involved with other vital functions in your body. They are part of wound healing, bone growth and forming new blood vessels.
There are two main types of mastocytosis. They are:
Mastocytosis, in particular systemic mastocytosis, is often caused by a mutation (a change in the code or sequence) in a gene called KIT. The change happens after conception. In most cases, it is not inherited (passed down from one generation to another).
If you have mastocytosis, certain activities and factors can trigger an attack. What causes an attack for one person may not affect someone else. There are dozens of potential triggers. You should talk to your doctor about medications and situations you should avoid.
Some common triggers include:
Mastocytosis can occur in children and adults. Systemic mastocytosis usually affects adults. Cutaneous mastocytosis typically appears in children, usually before the child’s second birthday. The condition affects males and females mostly equally.
Mastocytosis is rare. One estimate reports that it occurs in one in every 10,000 people, while another estimate is one in every 20,000 people.
Symptoms of mastocytosis can range from mild to severe. They include:
Your healthcare provider will ask about your symptoms and examine your skin. They may order urine or blood tests. To diagnose cutaneous mastocytosis, your provider will take a small skin sample and send it to a lab for testing. This procedure is called a skin biopsy.
Doctors may perform a bone marrow biopsy if they think you have systemic mastocytosis. They insert a needle into your bone and remove a sample of the bone marrow (spongy tissue inside your bones) and bone tissue. Your doctor will numb the area before the procedure. Before a biopsy, your healthcare provider may order a blood test to measure the basal serum total tryptase level. Mast cells release tryptase, an enzyme, when the cells are triggered.
There is no cure for mastocytosis, but treatments can help minimize symptoms. To manage it, you’ll need to avoid triggers that might cause an attack. Treatment for mastocytosis includes:
People with mastocytosis have a much higher chance of a life-threatening allergic reaction. Triggers such as medications, foods, and sudden changes in temperature (like jumping into cold water) can cause anaphylactic shock.
If you or your child has mastocytosis, you should talk to your doctor before you receive anesthesia. Many types of anesthesia can trigger a fatal allergic reaction.
Complications of systemic mastocytosis include:
Because mastocytosis is a genetic condition, there is no way to prevent it. If you have mastocytosis, you may be able to prevent an attack by avoiding foods, medications, and situations that trigger an outbreak.
Talk to your doctor about the triggers you should avoid. Triggers vary from person to person. Consider wearing a medical alert bracelet to notify others about medicines (such as anesthesia) you cannot take.
The outlook depends on the type of mastocytosis and how severe it is. Cutaneous mastocytosis is not life-threatening, but children who have it have a higher chance of a fatal allergic reaction. Cutaneous mastocytosis in children usually goes away or gets better by the time the child reaches puberty. This is why aggressive treatment is usually not necessary.
Systemic mastocytosis affects organs all over the body. That means it’s often more serious than cutaneous mastocytosis. The prognosis varies widely because systemic mastocytosis can range in severity.
People who have more aggressive cases of mastocytosis may not survive more than a few years after diagnosis. People with less aggressive mastocytosis have a typical life expectancy. They can usually manage the condition by avoiding triggers and taking antihistamines.
Last reviewed by a Cleveland Clinic medical professional on 09/17/2020.
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