Mastocytosis is a general term referring to a group of conditions with clinical features caused by mast cell infiltration of tissues and the release of chemical mediators, including histamine, prostaglandin D2, heparin, proteases, leukotrienes and chemotactic factors from these cells.
Mast cell degranulation, leading to the release of these substances, may be triggered by rubbing the lesions, fever and a number of drugs — including aspirin, morphine, codeine, d-tubocurarine, scopolamine, quinine, thiamine, procaine, polymyxin B and radiographic contrast media.
The effects of chemical mediator release may be local or systemic. Local effects include erythema and swelling (‘urtication’) of lesions on rubbing, surrounding dermographism, haemorrhage and blistering. Systemic effects include generalised flushing, tachycardia and hypotension.
This is a round- to oval-shaped,