In addition, the FIP1L1-PDGFRA fusion gene was detected only in these 2 cases.     ///    Clinical features of hypereosinophilic syndrome: FIP1L1-PDGFRA fusion gene-positive disease is a distinct clinical entity with myeloproliferative features and a poor response to corticosteroid..     ///    One of the FIP1L1-PDGFRA - positive HES cases featured bone marrow fibrosis.     ///    "Taken together, our data and previous reports suggest that FIP1L1-PDGFRA - positive HES is a distinct clinical entity with myeloproliferative features and showing a poor response to corticosteroid treatment.. "