Could you please explain what systemic mastocytosis is?

Is it a type of blood cancer? Is there any prescribed treatment? Is it terminal?

I cannot find any reference to this on the web.


Systemic mastocytosis is an uncommon condition involving a certain type of body cell known as a mast cell.

Mast cells are found in the connective tissue that surrounds and supports the more ordered tissues and organs of the body.

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Cartilage, bone and blood are specialised examples of connective tissue.

Mast cells mediate the skin's response to mild mechanical injury, producing immediate reddening of the skin due to the release of a chemical called histamine from granules within the cell.

An over production of mast cells can occur at any age and is seen slightly more often in males. The exact prevalence of systemic mastocytosis is not known and there has been no link made to it being a familial condition.

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 haematological 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 leukaemia' is the rarest form of the disease and is invariably fatal.

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 per cent or more patients with indolent systemic mastocytosis.

The diagnosis is suspected first on the clinical history and physical findings. A 24-hour 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.

Yours sincerely,

The NetDoctor Medical Team

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