Congenital and childhood myeloproliferative disorders with eosinophilia responsive to imatinib.

Eosinophilia is seen in several myeloproliferative disorders (MPD). A subset of MPD involves the platelet-derived growth factor receptor beta (PDGFRB) gene. Imatinib mesylate has been efficacious in treating some of these MPDs. Here we describe two patients with MPD with eosinophilia and PDGFRB rearrangements, one of which was congenital. Both patients were treated with single agent imatinib and continue to be in clinical, hematologic, and cytogenetic remission despite weaning doses. No definite guidelines currently exist regarding the exact dosing and duration of imatinib therapy for these patients.