Hypereosinophilic SyndromeEosinophiliaEosinophilsReceptor, Platelet-Derived Growth Factor alphamRNA Cleavage and Polyadenylation FactorsSyndromePediatricsInterleukin-5Eosinophil Granule ProteinsChurg-Strauss SyndromeBenzamidesChemokine CCL17Endomyocardial FibrosisPiperazinesPyrimidinesMastocytosisPulmonary EosinophiliaMastocytosis, SystemicPrednisolonePrednisoneOncogene Proteins, FusionAdrenal Cortex HormonesMyeloproliferative DisordersFatal OutcomeHydroxyureaLeukocyte Count