Neonatal Aggressive Systemic Mastocytosis Treated With Midostaurin and Systematic Review of the Literature

We describe a rare case of aggressive systemic mastocytosis (ASM) in a preterm neonate born at 33 weeks' gestation, with prenatal findings of polyhydramnios and hepatosplenomegaly. Postnatal evaluation revealed extensive cutaneous lesions. Her skin and liver biopsies confirmed mast cell infiltration. Molecular analysis identified a somatic KIT D816V mutation. Treatment with midostaurin, a multikinase inhibitor, led to significant clinical improvement, including resolution of skin lesions and reduction in hepatosplenomegaly. This case highlights the importance of early recognition of cutaneous signs in neonatal ASM and supports the potential role of targeted therapy with midostaurin.