Systemic mastocytosis, often termed systemic mast cell disease (SMCD), is a clonal disorder of the mast cell and its precursor cells. The clinical symptoms and signs of systemic mastocytosis (systemic mast cell disease) are due to the accumulation of these clonally derived mast cells in different tissues, including bone marrow, skin, the gastrointestinal (GI) tract, the liver, and the spleen.
The clinical symptoms a patient experiences when suffering from the condition are due to the mass of mast cells present in the tissue concerned and include recurrent headaches, itching, flushing, palpitations and fainting, gastric ulcer disease and lower abdominal crampy pain. These systemic changes contribute to bone pain and malabsorption and produce small, reddish brown macules or papules, termed urticaria pigmentosa within the skin which are present in 90 percent or more patients with indolent systemic mastocytosis.
Possible triggers of Mastocytosis includes:
- Physical stimuli, eg heat, cold, friction, sunlight, fatigue, exercise or fever.
- Emotional stimuli, eg stress.
- Certain foods, eg cheese, spices, shellfish, food preservatives, flavourings and colourings, monosodium glutamate.
- Environmental toxins, eg perfumes, pesticides.
- Insect bites, jelly fish stings, snake bites.
- Infection (bacterial, fungal or viral).
- Drugs, eg alcohol, anaesthetic agents, dextran, aspirin and non-steroidal anti-inflammatory drugs (NSAIDS), antibiotics, opioids, thiamine, quinine, gallamine, procaine, some radiographic dyes,polymyxin B, scopolamine and tubocurarine
The diagnosis is suspected first on the clinical history and physical findings. A 24-h urine collection for measurement of histamine and other metabolites, blood levels of histamine or the mast cell-derived neutral protease tryptase assist in confirming things. Additional investigations may be required depending on the clinical symptoms. Obviously a tissue diagnosis is easy if the skin lesions are present, but to confirm a diagnosis of the systemic involvement of other organs a bone marrow biopsy and aspiration is often performed.
Systemic mastocytosis is classified into four forms:
- The majority of patients have what is referred to as an 'Indolent' form that is not known to alter life expectancy and the associated clinical findings define their treatment and management.
- If the blood system is involved ('associated haematologic disorder'), then the nature of the blood disorder dictates the treatment required and the prognosis which can vary widely.
- In 'Aggressive Systemic mastocytosis' the liver, spleen and lymphatic system are involved and the prognosis is poor.
- 'Mast cell Leukemia' is the rarest form of the disease and is invariably fatal.