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Mastocytosis is a rare multisystem disorder of increased mast cell numbers in the skin and other tissues. Molecular genetic analysis of bone marrow reveals a mutation of KIT in nearly all adult patients with systemic disease. Although mastocytosis is primarily a haematological disorder, it often presents with skin lesions to dermatologists or paediatricians. Patients may also present with symptoms or complications of the disease to allergists, metabolic bone disease specialists or accident and emergency departments. A diagnosis of mastocytosis can be confirmed by lesional skin biopsy. Systemic mastocytosis is usually diagnosed by bone marrow biopsy. Local or systemic symptoms from mast cell mediator release are common. Complications of adult disease include anaphylaxis, osteoporosis and the lifetime development of associated haematological non‐mast cell diseases. At least 50% of children will grow out of mastocytosis by puberty, particularly those with early‐onset disease. Treatment is aimed primarily at symptom control with antimediator drugs, including H1 antihistamines, but patients with advanced systemic disease may require cytoreductive drugs.
Keywords mastocytosis, urticaria pigmentosa, telangiectasia macularis eruptive perstans, diffuse cutaneous mastocytosis, mastocytoma, tryptase, D816V KIT mutation