Mastocytosis
Mastocytosis is a rare condition in which too many mast cells build up in the tissues. The body needs these cells, but when there are too many they empty…
On this page
- Mast cells and why they end up in excess
- The skin form: what shows on the skin
- The systemic form: episodes and variants
- What sets an episode off
- Anaphylaxis: when to call an ambulance
- How the diagnosis is made
- Easing the day-to-day symptoms
- Treating the severe forms
- Surgery, anaesthesia and other precautions
- Online consultation with a doctor
Medicines commonly prescribed for Mastocytosis
For informational purposes only. Always consult a doctor before using any medicine.
Dosage form: INJECTABLE, 15 mg/1.5 mlActive substance: somatropinManufacturer: Novo Nordisk A/SPrescription requiredDosage form: TABLET, 40 mgActive substance: pantoprazoleManufacturer: Laboratorios Francisco Durban S.A.Prescription requiredDosage form: TABLET, 20 mg of pantoprazoleActive substance: pantoprazoleManufacturer: Takeda GmbhPrescription not required
Mastocytosis is a rare condition in which too many mast cells build up in the tissues. The body needs these cells, but when there are too many they empty their contents all at once from time to time and a wave of symptoms follows. In children the condition usually stays in the skin and fades with age. In adults the cells settle in the bone marrow and other organs, and that is a lifelong state — though most people with it lead an ordinary life.
Mast cells and why they end up in excess
Mast cells are born in the bone marrow and spread through the tissues that meet the outside world: the skin, the lining of the airways and the gut, the walls of blood vessels. Inside they carry granules of histamine, of the enzyme tryptase and of dozens of other substances. When a cell picks up an alarm signal it releases that content: vessels widen, the skin reddens and itches, smooth muscle contracts. This is normal defence, and allergic reactions come from the same mechanism.
In mastocytosis one such cell develops a fault in the KIT gene, most often the change known as D816V. The gene controls a receptor through which the cell is told to grow and stay alive. The faulty receptor works of its own accord, with no instruction at all, and the descendants of that cell multiply and fail to die on schedule.
The fault arises inside the person's own body rather than being inherited from a parent: mastocytosis is not catching, almost never passes to children and is not the result of anything anyone did or failed to do. Family cases have been described, but they are exceptionally rare.
The skin form: what shows on the skin
Cutaneous mastocytosis is almost always a childhood story and most often begins in the first year of life. Reddish-brown patches and small bumps appear on the skin, usually on the trunk, the arms and the legs and less often on the face and neck. They range from a millimetre to several centimetres, and the number varies hugely: one child has five, another too many to count.
There is a telling feature: stroke one of these patches gently and it swells, reddens and starts to itch like a nettle rash. This is Darier's sign, an important clue for the doctor. Do not rub hard, especially in babies, because a blister forms over the lesion easily.
Small children may have other variants. A mastocytoma is a single firm nodule that can rise into a blister. Diffuse cutaneous mastocytosis is rare and the most serious: almost all the skin is thickened, blisters come up from rubbing, nappies and bathing, and such a child needs constant specialist supervision.
The childhood skin form clears on its own in most cases by adolescence. In adults, by contrast, the lesions usually stay for years and often turn out to be the visible part of a systemic form.
The systemic form: episodes and variants
In the systemic form the cells live in the bone marrow, the liver, the spleen, the gut and the bones. Many people feel well most of the time, and the trouble arrives in episodes lasting anything from a few minutes to a couple of hours. During an episode there may be:
- sudden flushing of the face, neck and upper chest with a feeling of heat;
- forceful or fast palpitations, dizziness, vision going dark;
- sharp cramping in the abdomen, nausea, vomiting and diarrhoea;
- itching, weals, swelling of the eyelids and lips;
- headache, weakness, irritability and difficulty concentrating.
Alongside the episodes there can be constant complaints: pain in the bones and joints, heartburn and pain high in the abdomen from excess acid, and tiredness. The bones lose density, and osteoporosis with a crushed vertebra is often what brings a person to a doctor in the first place.
There are several variants. In nine people out of ten it is the indolent form: it does not shorten life, although it spoils its quality. Less common are the aggressive form, in which the cells disrupt the liver, spleen, bone marrow and gut, and the variant that comes with a blood disease in its own right; very rarely there is mast cell leukaemia. Everything about treatment depends on which variant a person has, and only a specialist can tell them apart.
What sets an episode off
Triggers differ from person to person, so the first thing worth doing after diagnosis is keeping a diary: what was eaten, drunk and done before the episode. After a month or two the pattern usually shows. The commonest provocations are:
- overheating, a very hot bath, a sauna, sudden chilling, and friction on the skin from a rough flannel or tight clothing;
- exercise to exhaustion, too little sleep and severe upset;
- alcohol, wine in particular;
- spicy food, mature cheeses, smoked foods and shellfish;
- wasp and bee stings;
- infections with a high temperature;
- certain medicines.
Medicines deserve a closer look, because it is easy to go to extremes here. In some people an episode is set off by anti-inflammatory painkillers, opioid painkillers, iodine-containing contrast agents and certain anaesthetic drugs. In others those same medicines are tolerated perfectly well, and a few are even prescribed aspirin under supervision to reduce flushing. The rule is this: do not stop on your own something you tolerate, and do not start a new medicine without discussing it with your doctor.
If a severe reaction has already followed a wasp or bee sting, it can be prevented: venom immunotherapy exists. In mastocytosis it is continued for life and markedly lowers the risk of another anaphylaxis.
Anaphylaxis: when to call an ambulance
The risk of a severe allergic reaction is higher here than usual, and it often unfolds without any rash and without obvious contact with an allergen, so do not wait for the familiar nettle rash.
Call an ambulance at once if any of these come on suddenly:
- difficult, wheezy breathing, a sense of the throat closing, a hoarse voice;
- swelling of the lips, tongue or eyelids and trouble swallowing;
- abrupt weakness, faintness, collapse, the ground seeming to go from under you;
- pale clammy skin with a fast weak pulse;
- severe cramping abdominal pain with vomiting and diarrhoea alongside general weakness.
If you have been given an adrenaline auto-injector, use it straight away into the outer thigh, through clothing if need be, and only then make the call: delay is more dangerous than an unnecessary injection. After the injection lie down and raise your legs; do not stand up suddenly. If there is no improvement after five to fifteen minutes a second dose is given, which is why two auto-injectors are carried. Go to hospital in any case, even if you feel better, because the reaction can return hours later. In Spain, Italy, Portugal, Poland and Ukraine an ambulance is called on the single European number 112; elsewhere use your national emergency number.
How the diagnosis is made
With the skin it is relatively straightforward: a dermatologist examines the lesions, checks for Darier's sign and takes a biopsy — under the microscope the clusters of mast cells are visible, and a special stain confirms that is what they are.
Next comes the question of whether there is a systemic form. The first step is a blood tryptase level taken away from an episode. A persistently raised figure means looking further, but on its own it is not a diagnosis: tryptase rises for other reasons, including in healthy people with an inherited quirk. At the same time a full blood count and liver tests are checked and an abdominal ultrasound scan is done.
The decisive investigation is a bone marrow biopsy. A needle takes a core of bone and a drop of marrow, usually from the pelvis, under local anaesthetic. The sample is examined for the characteristic clusters of mast cells, for unusual proteins on their surface and, by highly sensitive methods, for that KIT mutation. The mutation can now also be found in blood, which sometimes saves a step.
Bone density is checked by a scan: osteoporosis develops early here and goes unnoticed until the first fracture. Years often pass between the first symptoms and the diagnosis, because flushing, faints and abdominal pain are explained away by a dozen other causes. If the picture does not add up and tryptase is raised, it is worth approaching a centre that deals with this condition specifically.
Easing the day-to-day symptoms
In most variants the surplus cells cannot be removed for good, so the main work is directed against the symptoms, and it is done fairly successfully.
The mainstay is antihistamines that block type one receptors. They are taken continuously rather than as needed, often at higher than standard doses, and the modern non-drowsy ones are preferred. For heartburn, pain high in the abdomen and diarrhoea, drugs that reduce stomach acid are added. For persistent itching and flushing there are medicines that stabilise the mast cell membrane and others that block the action of leukotrienes.
Severe skin itching in adults is treated with light therapy using ultraviolet of a particular waveband; the number of sessions is capped, because too much ultraviolet raises the risk of skin tumours. Steroid ointments are used in short courses on individual lesions rather than over the whole skin, since prolonged use thins the skin. Steroid tablets are prescribed rarely and briefly, for a severe flare. For osteoporosis, bisphosphonates are given along with calcium and vitamin D.
Simple measures help too: not overheating, wearing loose clothes in soft fabric, washing in warm rather than hot water and protecting the skin from friction.
Treating the severe forms
When the cells disrupt how organs work, symptom relief alone is not enough and medicines that suppress the mast cells themselves are needed.
The mainstay today is targeted tyrosine kinase inhibitors, which block that very faulty receptor. Midostaurin is used in advanced systemic mastocytosis; avapritinib acts directly on the D816V mutation and is used both in advanced forms and in severe indolent disease. Imatinib stands apart: against the D816V variant it is powerless and it suits only the small minority of patients who do not carry that mutation, which is why the mutation is always tested for before it is prescribed.
Among the older drugs, interferon alfa and cladribine retain a place and are used when the targeted agents are unavailable or have not worked. All of these require regular blood tests and haematology follow-up, and some weaken defence against infection: with a high temperature or shivering, contact a doctor the same day. If mastocytosis comes with a blood disease of its own, both are treated; in mast cell leukaemia a bone marrow transplant is considered.
Surgery, anaesthesia and other precautions
Planned procedures — operations, dental treatment, scans with contrast, childbirth — are arranged in advance, and the anaesthetist is always told the diagnosis. Most of the time everything passes quietly, but the team needs to be ready: antihistamines of both types are often given beforehand, sometimes with a steroid added, and anaesthetic drugs are chosen from those least likely to provoke a release.
Always carry two adrenaline auto-injectors if your doctor has prescribed them, and keep an eye on the expiry date. A card or a bracelet stating the diagnosis is useful: if you are unconscious it is the only way to make it known. Family and colleagues should know where the auto-injector is kept and how to use it.
Vaccinations are not contraindicated and are given on the usual schedule; you are simply asked to wait under observation for a while afterwards. Sport is allowed as long as you avoid exhaustion and overheating.
Online consultation with a doctor
Mastocytosis is a condition where much of a doctor's work is going through findings and explaining them, and that transfers well to a remote appointment. Online you can work through a tryptase result and a biopsy report, understand which investigation logically comes next, build a personal trigger list from your diary and settle in advance what to do during an episode. A frequent topic is how to prepare for an operation or a scan with contrast and exactly what to tell the anaesthetist. Upload your test results, reports and photographs of the lesions taken in good light beforehand. With signs of anaphylaxis an online appointment is no use: what is needed is adrenaline and an ambulance.
This material is for information only and does not replace medical advice.
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