Five male patients with splenomegaly carried the FIP1L1-PDGFRA gene rearrangement.     ///     Eosinophilia associated with FIP1L1-PDGFRA rearrangement represents a subset of chronic eosinophilic leukemia and affected patients are sensitive to imatinib treatment.     ///    This study was undertaken to learn the prevalence and associated clinicopathologic and genetic features of FIP1L1-PDGFRA rearrangement in a cohort of 26 adult patients presenting with profound eosinophilia (>1.5x10(9)/L).     ///    Reverse-transcriptase polymerase chain reaction and gel electrophoresis were used for the detection of FIP1L1-PDGFRA rearrangement.     ///    This study indicates the need to do the FIP1L1-PDGFRA assay in patients with hypereosinophilic syndrome. 