• Mastocytosis is a mostly harmless condition where a greater number of mast cells than normal build up in parts of the body. Everyone has mast cells – they are found in the skin, bowels, gut (stomach), lungs and air passages. They play an important role in helping the immune system protect the body against diseases. Mast cells contain many different natural chemicals, including histamine.

    Heat, rubbing and certain foods or medications cause mast cells to release their contents. In children with mastocytosis, more chemicals are released than their body needs because they have extra mast cells.

    Mastocytosis can come on at any age, but childhood mastocytosis is different to the mastocytosis that adults get. In children, mastocytosis most commonly affects the skin. Mastocytosis in the skin is also called urticaria (er-tuh-care-ia) pigmentosa. It is very rare for children to have extra mast cells in other parts of their body.

    Signs and symptoms of mastocytosis

    For children with mastocytosis, the extra mast cells do not usually cause problems, and almost half of all children affected will have no symptoms. When symptoms are present, they can range from very minor to severe, and may include the following: 

    • The skin will have one or many pink or brown spots, which may be flat or raised. The spots may be anywhere on the body, but are most commonly found on the torso and limbs. As the condition gets better, the spots often fade, but they may remain for years.
    • When the mast cells in the skin release their chemicals, the spots can become itchy, red and swollen (like hives), and occasionally the spots may even form blisters. This is more common after the spots are rubbed or exposed to heat.
    • If there are only one or two spots, the chemicals released by the mast cells are not enough to cause other problems. If there are many spots on the skin, other possible symptoms can include flushing (reddening of the skin), irregular heartbeat, tiredness, headaches, diarrhoea, stomach pain, ulcers, nausea and vomiting. 
    • Very rarely, reactions such as light-headedness, breathing difficulties, wheezing and even fainting may occur.

    When to see a doctor

    If your child has symptoms of mastocytosis, take them to the GP. Sometimes a blood or skin test is required to confirm the diagnosis of mastocytosis and determine the extent of the condition.

    If your child has more than a few spots, they should have regular check-ups with their GP or dermatologist. Your child's growth and development should also be checked regularly, however it’s uncommon to have problems associated with mastocytosis.

    Care at home

    Mastocytosis in children is likely to go away by itself after several years. Seven out of 10 children with mastocytosis affecting their skin can expect a big improvement by the time they are 10 years old.

    Often no medication is needed for mastocytosis. However, antihistamines may be used to relieve symptoms such as itching, and topical cortisone creams have been found to be helpful. You can buy these from your local chemist. You could also try applying cold, wet compresses to relieve the itch.

    It is important to be aware of the things that trigger or cause a response in your child, and avoid them if possible. Triggers may include:

    • excess heat
    • drinking hot liquids
    • swimming in cold water
    • being emotional or stressed
    • some medications and food. 

    Exercise can also trigger a response for some children, and while exercise should not be avoided, you should be aware that it may cause symptoms in your child.


    Some medications can stimulate mast cells to release histamine (e.g. some pain relievers, cough medicines and anaesthetics can cause problems). It is better that your child avoids these. Always check medications with your child's doctor or pharmacist before giving them to your child. If your child is having surgery, inform the anaesthetist about the mastocytosis.


    Some children find that large amounts of certain foods can also cause a flare up of the condition. Your child's doctor will explain what foods should be avoided and you can work with a paediatric dietician to supplement your child's diet with safe alternatives.

    What causes mastocytosis?

    The cause of mastocytosis is not known. A problem with a gene has been found in some patients, but mastocytosis is not usually passed on from one generation to the next. It is not contagious, and is not spread by contact with other people.

    Key points to remember

    • Mastocytosis in children is usually a harmless condition that goes away over some years.
    • Some children have no symptoms, and some have pink or brown spots on their skin.
    • Mastocytosis can't be caught by others and is not usually passed on from one generation to the next.
    • Adult mastocytosis is different to childhood mastocytosis.

    For more information

    Common questions our doctors are asked

    When is mastocytosis usually diagnosed?

    More than 80 per cent of children with mastocytosis are diagnosed in their first year of life, and they will usually have an increase in mast cells in their skin only. When mastocytosis starts in adulthood, it tends to affect other parts of the body, too.

    My child has mastocytosis. Is she likely to also have anaphylaxis?  

    The skin reaction of mastocytosis can resemble allergy, but the triggers are often different. Children with mastocytosis do not need to have an EpiPen. However, there is an increased risk of anaphylaxis in children with mastocytosis. You should discuss anaphylaxis management with your child's doctor.   

    Should I keep my child away from child care when his mastocytosis is flaring up?

    Mastocytosis is not contagious, so he won’t spread it to any other children. If he is otherwise feeling well, you can take your child to child care. 

    Is there any link between mastocytosis and cancer?

    You may have seen some information on the internet that mentions mastocytosis and cancer. This is not relevant to the type of mastocytosis that children get. It is also extremely rare. When reading up about mastocytosis, remember that information about adult mastocytosis may not be relevant to your child.

    Developed by The Royal Children's Hospital Dermatology department. We acknowledge the input of RCH consumers and carers.

    Reviewed July 2018.

    This information is awaiting routine review. Please always seek the most recent advice from a registered and practising clinician.

    Kids Health Info is supported by The Royal Children’s Hospital Foundation. To donate, visit


This information is intended to support, not replace, discussion with your doctor or healthcare professionals. The authors of these consumer health information handouts have made a considerable effort to ensure the information is accurate, up to date and easy to understand. The Royal Children's Hospital Melbourne accepts no responsibility for any inaccuracies, information perceived as misleading, or the success of any treatment regimen detailed in these handouts. Information contained in the handouts is updated regularly and therefore you should always check you are referring to the most recent version of the handout. The onus is on you, the user, to ensure that you have downloaded the most up-to-date version of a consumer health information handout.