We investigated the presence of KIT(M541L) in five males with chronic eosinophilic leukemia, not otherwise specified (CEL, NOS), all negative for Platelet-derived growth factor-alpha (PDGFR) or PDGFRbeta abnormalities, which responded to imatinib therapy.
The dysregulated tyrosine kinases, D816VKIT and FIP1L1-PDGFRA, are the prototypic oncogenic lesions resulting in systemic mastocytosis (SM) and chronic eosinophilic leukemia, respectively.
The broad and overlapping clinical manifestations of D816VKIT-associated systemic mastocytosis with eosinophilia and FIP1L1/PDGFRA-associated chronic eosinophilic leukemia (CEL), coupled with the increase in activated eosinophils and mast cells seen in both disorders, have led to confusion in the nomenclature.