The incidence of mastocytosis is closely related to KIT gene mutation.[2,3] The vast majority of cases are confined to the skin, with approximately 10% of cases involving organs other than the skin, mainly the bone, liver, spleen, GI tract, and lymph nodes.[1,3] The incidence of the disease is 0.01% and increases by 5 to 10 per million per year. The gene discussed is KIT; the disease is mastocytosis.