Mastocytosis
An overgrowth of mast cells causing allergy-like symptoms
Quick Facts
- Type: Mast cell disorder
- Main forms: Cutaneous and systemic
- Key chemical: Histamine and other mediators
- Severe reaction: Can cause anaphylaxis
Overview
Mastocytosis is a rare condition in which the body produces too many mast cells. Mast cells are part of the immune system and normally help defend against infection and play a role in allergic reactions. They store powerful chemicals, including histamine, that they release when triggered. In mastocytosis, the excess mast cells can release these chemicals more easily and in larger amounts, causing a range of symptoms.
There are two broad forms. In cutaneous mastocytosis, the extra mast cells are mainly in the skin, and this form is most common in children, often improving with age. In systemic mastocytosis, mast cells build up in organs such as the bone marrow, liver, spleen, or digestive tract, and this form is more common in adults. The severity ranges widely from mild and manageable to, rarely, more serious disease.
Symptoms
Symptoms come from the release of mast cell chemicals and from mast cells collecting in organs. They can vary from mild to severe and may flare in episodes.
- Flushing of the skin and a feeling of warmth
- Itching, hives, or brownish spots that swell when scratched
- Abdominal pain, nausea, diarrhea, or reflux
- Lightheadedness, a fast heartbeat, or fainting
- Headache, fatigue, and difficulty concentrating
- Bone or muscle pain in some people with systemic disease
In severe cases, mast cells can trigger a life-threatening allergic reaction called anaphylaxis, with swelling, trouble breathing, and a drop in blood pressure.
Causes
Mastocytosis is usually caused by a change in a gene that controls how mast cells grow and survive. This genetic change leads mast cells to multiply and accumulate. In most cases the change is not inherited but arises on its own, and the condition is not contagious.
Symptoms are often set off by triggers that prompt mast cells to release their chemicals. Common triggers include heat or cold, friction on the skin, certain foods or alcohol, insect stings, infections, emotional stress, and some medications.
Risk Factors
- Genetic changes affecting mast cell growth
- Childhood onset for many skin-limited forms
- Adulthood for many systemic forms
- A history of severe allergic reactions or unexplained anaphylaxis
Diagnosis
Diagnosis combines the pattern of symptoms with tests that detect excess mast cells or their chemicals.
- Skin examination and biopsy: To identify characteristic skin lesions and confirm mast cells in the skin.
- Blood tests: Measuring tryptase, a chemical that is often elevated in systemic mastocytosis.
- Bone marrow biopsy: Used in adults to confirm systemic disease and assess its extent.
- Genetic testing: To detect the specific gene change associated with the condition.
Treatment
There is no cure for most forms of mastocytosis, so treatment focuses on relieving symptoms, avoiding triggers, and preventing severe reactions.
- Antihistamines: Block the effects of histamine to ease flushing, itching, and stomach symptoms.
- Mast cell stabilizers and other medicines: Help reduce the release of mast cell chemicals.
- Emergency epinephrine: People at risk of anaphylaxis carry an epinephrine auto-injector and an action plan.
- Trigger avoidance: Identifying and steering clear of personal triggers.
- Targeted therapy: For advanced systemic disease, medicines that act on the underlying mast cell changes may be used.
Prevention
Mastocytosis itself cannot be prevented, but symptom flares and dangerous reactions often can be reduced.
- Learn your personal triggers and avoid them
- Take prescribed antihistamines and other medicines consistently
- Carry an epinephrine auto-injector if you are at risk of anaphylaxis
- Tell all your healthcare providers about your condition before procedures or new medicines
- Wear medical identification noting your mast cell disorder
When to See a Doctor
See a doctor if you have repeated unexplained flushing, itching, hives, or stomach symptoms, or unexplained fainting. Call emergency services immediately for signs of anaphylaxis:
- Difficulty breathing, wheezing, or throat tightness
- Swelling of the lips, tongue, or face
- Sudden dizziness, fainting, or a feeling of impending collapse
- A widespread rash with these symptoms
Use an epinephrine auto-injector if prescribed and then seek emergency care.
Frequently Asked Questions
What do mast cells do?
Mast cells are immune cells that help defend against infection and drive allergic reactions. They store chemicals such as histamine and release them when triggered. In mastocytosis there are too many mast cells, so these chemicals are released more easily.
Is mastocytosis cancer?
Most forms of mastocytosis are not cancer. However, because it involves an overgrowth of mast cells, certain rare, advanced forms can behave more aggressively. A doctor uses biopsies and other tests to determine the type and how serious it is.
Can mastocytosis cause life-threatening reactions?
Yes. In some people, mast cells can trigger anaphylaxis, a severe allergic reaction with breathing trouble, swelling, and a drop in blood pressure. People at risk should carry an epinephrine auto-injector and seek emergency care if it occurs.
Does childhood mastocytosis go away?
Many children with skin-limited mastocytosis improve or have symptoms fade as they grow, often by the teenage years. Systemic forms, more common in adults, tend to be long-lasting and are managed rather than cured.
What triggers mastocytosis symptoms?
Common triggers include heat, cold, friction on the skin, certain foods and alcohol, insect stings, infections, stress, and some medications. Identifying and avoiding personal triggers is an important part of managing the condition.
References
- National Organization for Rare Disorders (NORD). Mastocytosis.
- Mayo Clinic. Mastocytosis.
- MedlinePlus, U.S. National Library of Medicine. Mastocytosis.
- American Academy of Allergy, Asthma & Immunology (AAAAI). Mastocytosis.