 Patients with primary hypereosinophilic disorders who are positive for the FIP1L1-PDGFRA fusion gene mutation are highly responsive to therapy with imatinib mesylate.     ///    Maintenance therapy with imatinib appears necessary despite molecular remission in FIP1L1-PDGFRA fusion gene positive hypereosinophilic disorder..     ///    "A 35-year-old man with FIP1L1-PDGFRA positive hypereosinophilic syndrome and cardiac involvement, was treated with imatinib 100 mg daily. "    ///    Our experience and a review of limited literature suggest that imatinib maintenance therapy is necessary despite molecular remission of the FIP1L1-PDGFRA mutation.. 