Mastocytosis
What is Mastocytosis?
Mastocytosis is a rare condition where too many mast cells build up in your body. Mast cells are part of your immune system. They normally help protect you from infections and allergies. When you have mastocytosis, these cells gather in your skin, organs, or bone marrow in higher numbers than normal.
These extra mast cells can release large amounts of histamine and other chemicals into your bloodstream. Histamine is a substance that causes allergic reactions. When mast cells release too much histamine, you can experience symptoms similar to a severe allergic reaction. These symptoms can range from mild skin rashes to serious reactions that affect your whole body.
There are two main types of mastocytosis. Cutaneous mastocytosis affects mainly the skin and is more common in children. Systemic mastocytosis affects internal organs and bone marrow and occurs more often in adults. Most children with the skin form grow out of it by adulthood. Adults with the systemic form usually need ongoing monitoring and treatment.
Symptoms
- Brown or red skin spots or patches that may itch or swell when rubbed
- Flushing or sudden redness of the face and neck
- Severe itching all over the body
- Hives or raised welts on the skin
- Abdominal pain, cramping, or diarrhea
- Nausea and vomiting
- Rapid heartbeat or low blood pressure
- Bone pain or fractures
- Headaches or brain fog
- Severe allergic reactions to insect stings, foods, or medications
Some people with mild mastocytosis may have few or no symptoms for long periods. Others experience symptoms daily that can interfere with normal activities. Symptoms often get worse when mast cells are triggered by heat, cold, stress, exercise, alcohol, certain medications, or insect stings.
Concerned about Mastocytosis? Check your levels.
Screen for 1,200+ health conditions
Causes and risk factors
Mastocytosis happens due to genetic changes in mast cells that cause them to grow and multiply too much. Most cases involve a mutation in the KIT gene. This gene controls how mast cells develop and function. The mutation causes mast cells to grow out of control and live longer than normal. In most cases, this mutation is not inherited from parents. It happens spontaneously during a person's lifetime.
Risk factors for mastocytosis are not well understood because the condition is rare. It can develop at any age but most often appears in childhood or adulthood. Family history plays a role in very rare cases where the genetic mutation is inherited. Men and women appear to be affected equally. Unlike allergies, mastocytosis is not caused by environmental exposures or lifestyle factors. However, certain triggers can make symptoms worse once you have the condition.
How it's diagnosed
Diagnosing mastocytosis requires specialized testing beyond routine blood work. Your doctor will start with a physical exam looking for characteristic skin lesions. A skin biopsy is often the first diagnostic test. This involves taking a small sample of affected skin to examine under a microscope for excess mast cells.
For suspected systemic mastocytosis, a bone marrow biopsy is usually needed to confirm the diagnosis. Blood tests can measure serum tryptase, a chemical released by mast cells that is often elevated in people with mastocytosis. Plasma histamine levels may also be checked, as mast cells release histamine when they are activated. Additional tests may include genetic testing for the KIT gene mutation and imaging studies to check for organ involvement. Talk to your doctor about specialized testing if you have symptoms that suggest mastocytosis.
Treatment options
- Antihistamines to block the effects of histamine and reduce itching, flushing, and hives
- Mast cell stabilizers like cromolyn sodium to prevent mast cells from releasing histamine
- Epinephrine auto-injectors for people at risk of severe allergic reactions or anaphylaxis
- Proton pump inhibitors or H2 blockers to reduce stomach acid and treat digestive symptoms
- Avoiding known triggers such as extreme temperatures, alcohol, spicy foods, and certain medications
- Stress management techniques to reduce symptom flares
- Sun protection and gentle skin care to minimize skin irritation
- Tyrosine kinase inhibitors or other targeted therapies for advanced systemic disease
- Regular monitoring by a specialist in hematology or allergy and immunology
Frequently asked questions
Cutaneous mastocytosis affects primarily the skin and is more common in children. It often appears as brown or red spots that may itch or swell. Systemic mastocytosis involves internal organs, bone marrow, and sometimes the skin. It occurs more often in adults and usually requires ongoing medical management.
No, mastocytosis is not the same as allergies. Mastocytosis is a rare condition where you have too many mast cells in your body. While the symptoms can be similar to allergic reactions, the underlying cause is different. People with mastocytosis may be more prone to severe allergic reactions.
There is no cure for mastocytosis in most adults. However, cutaneous mastocytosis in children often resolves on its own by adulthood. Treatment focuses on managing symptoms and preventing severe reactions. Most people with mastocytosis can live normal lives with proper treatment and trigger avoidance.
Common triggers include extreme hot or cold temperatures, alcohol, spicy foods, certain medications, physical friction on the skin, stress, and insect stings. Some people react to specific foods or food additives. Keeping a symptom diary can help you identify your personal triggers so you can avoid them.
Diagnosis typically involves a skin biopsy to look for excess mast cells. For systemic mastocytosis, a bone marrow biopsy is usually needed. Blood tests measuring serum tryptase and plasma histamine levels can support the diagnosis. Genetic testing for KIT gene mutations may also be performed.
Many people with mastocytosis are prescribed an epinephrine auto-injector because they are at higher risk for severe allergic reactions and anaphylaxis. Your doctor will assess your individual risk based on your symptoms and type of mastocytosis. Always carry your injector if prescribed and know how to use it.
Yes, systemic mastocytosis can affect bone health. Mast cells in the bone marrow can weaken bones and increase fracture risk. Some people experience bone pain as a symptom. Your doctor may recommend bone density scans and supplements like calcium and vitamin D to protect your bones.
Serum tryptase is the most common blood test used to monitor mastocytosis. Elevated levels suggest active disease or mast cell activation. Plasma histamine levels can also be measured, especially during symptom flares. Your doctor may order these tests periodically to track your condition and treatment response.
In most cases, mastocytosis is not inherited. The genetic mutation that causes it usually happens spontaneously and is not passed down from parents. In very rare familial cases, the condition can be inherited. If you have concerns, talk to a genetic counselor about your specific situation.
While diet cannot cure mastocytosis, avoiding trigger foods can help reduce symptoms. Many people benefit from avoiding alcohol, spicy foods, aged cheeses, processed meats, and foods high in histamine. Some find that eating fresh, whole foods and avoiding additives helps. Work with your doctor or a dietitian to develop a plan that works for you.