In some patients, it is possible todiagnose more advanced SM types, such as aggressive SM, SM associatedwith hematologic neoplasm, and mast cell leukemia.3,7 Anessential role in the onset of mastocytosis seems to be played byKIT,8 the tyrosine kinase receptor expressedon mast cell membranes that regulates the survival of mast cells byinteracting with the stem cell factor. This evidence concerns the gene NTRK1 and systemic mastocytosis.