Mastocytosis are orphan diseases characterized by the accumulation of mast cells in one or more organs. A distinction is made between systemic forms (10 %) and pure cutaneous forms (90 %), the latter being mainly pediatric and generally having a spontaneously favourable prognosis. In the absence of a systemic sign, the diagnostic criteria for cutaneous mastocytosis are Darier's sign, in principle, pathognomonic, as well as skin histology confirming mast cell infiltration. The treatment is essentially preventive (avoidance of factors triggering degranulation) and symptomatic (antihistamine agents).