Since constitutive activation of the KIT tyrosine kinase receptor as a consequence of gain-of-function mutations in the KITgene (most frequently D816V) is considered a disease-driving event in the pathogenesis of SM [5–9], the multikinase inhibitor midostaurin, that targets both wild-type and mutant KIT, has been tested in clinical trials and recently approved for use in patients with AdvSM [10, 11]. Here, KIT is linked to systemic mastocytosis.