Medicines for Mastocytosis

What it is

Mastocytosis is a rare condition in which there is a build-up of too many mast cells in the body. Mast cells are a type of immune cell, normally involved in the body’s responses to allergens and in inflammation; they contain chemicals (such as histamine) that they release, causing effects like itching, flushing, and swelling. In mastocytosis, the excess mast cells, and the chemicals they release (especially when triggered), cause the symptoms of the condition. There are two broad categories: cutaneous mastocytosis, where the excess mast cells are mainly in the skin (this is more common, especially in children, and often milder); and systemic mastocytosis, where mast cells build up in other parts of the body (such as the bone marrow and internal organs) as well as, or instead of, the skin (this is more common in adults and can range from mild to more significant). The symptoms depend on the type and where the mast cells are, and on the release of their chemicals, and can include: skin symptoms (such as itchy skin, brown or reddish spots or patches that can itch, flush, or swell when rubbed); flushing (reddening of the skin); itching; tummy symptoms; and, when large amounts of mast cell chemicals are released (for example triggered by certain factors), more significant symptoms up to, in some people, severe allergic-type reactions (anaphylaxis). Triggers that can cause mast cells to release their chemicals vary between individuals but can include things such as heat or temperature changes, friction or rubbing the skin, certain foods or drinks, insect stings, some medicines, stress, and others. Mastocytosis varies greatly in severity — many people, particularly children with the skin form, have mild disease that may improve over time, while systemic forms in adults can be more variable, and rare forms can be more serious. There is no cure for most forms, but the condition is managed by controlling symptoms, avoiding triggers, and, for those at risk of severe reactions, being prepared to treat them; specialist care guides management. The key messages are that mastocytosis is a rare condition with too many mast cells, causing symptoms such as itching and flushing (and, in some, more significant reactions), and that it is managed by controlling symptoms, avoiding triggers, and preparedness for severe reactions.

How it is treated

Mastocytosis is managed by controlling the symptoms, avoiding triggers that cause mast cells to release their chemicals, and — for those at risk of severe reactions — being prepared to treat them, with specialist care guiding management; treatment is tailored to the type and severity. Diagnosis involves assessment of the symptoms and skin changes, and tests — which may include a skin biopsy (for the skin form), blood tests (such as measuring a marker of mast cells called tryptase), and, for suspected systemic mastocytosis, a bone marrow test and other investigations — to confirm the diagnosis, determine the type, and assess the extent; specialist assessment is important. Management then focuses on: controlling symptoms — antihistamines are a mainstay, as they block the effects of histamine released by mast cells and help with itching, flushing, and other symptoms; and other medicines are used depending on the symptoms (for example, treatments for tummy symptoms, or other symptom-specific treatments), as advised by specialists. Avoiding known triggers is an important part of management, as it reduces symptoms and the risk of significant mast cell activation: individuals identify and avoid their own triggers where possible (which may include things such as extreme temperatures, friction, certain foods, alcohol, some medicines, insect stings, or stress), and are given advice on this. For people at risk of severe allergic-type reactions (anaphylaxis) — which can occur in some people with mastocytosis, particularly if a lot of mast cell chemicals are released — an important part of care is being prepared: carrying adrenaline auto-injectors and knowing how and when to use them, having an emergency plan, avoiding triggers, and, where relevant, taking precautions (for example around insect stings or certain medicines); this is potentially life-saving. For more significant or systemic disease, specialists monitor and manage the condition, and, for the rarer more serious forms, specific treatments may be needed. In children with the skin form, the condition often improves or resolves over time, and management focuses on symptoms and triggers. Support and information help people manage a rare, long-term condition. The reassuring messages are that mastocytosis, although rare and lifelong for many, is usually managed by controlling symptoms (with antihistamines and other treatments), avoiding triggers, and, for those at risk, being prepared to treat severe reactions, that many people (especially children with the skin form) have milder disease, and that specialist care guides management; so identifying triggers, controlling symptoms, and preparedness (where needed) are the keys to living with mastocytosis.