Yes. There are no accurate data on the frequency of mastocytosis. Annual incidence of 5-10 new cases per million population is estimated. In dermatological practices and hospital departments of dermatology, 1 of every 1000 to 8000 new patients has mastocytosis. The most frequently encountered forms are cutaneous mastocytosis and indolent systemic mastocytosis. The least common is mast cell leukemia.