Systemic mastocytosis is a myeloproliferative disorder characterized by growth and accumulation of abnormal mast cells in one or more organs. The symptoms of the disease are due both to the mast cells infiltrating the organs and to the action of its degranulation products. Over 85% of adult patients exhibit point mutations of KIT at position 816 (D816V). Systemic mastocytosis is rare in both adults and children, so treatment is highly individualized; therapy and further treatment is adjusted to each patient's needs. The aim of this study was to present the case of a 14-year old female with systemic mastocytosis and the problems with her treatment. Multidisciplinary management is recommended in systemic mastocytosis.