A fluorescence in situ hybridization (FISH)-based strategy was used to detect FIP1L1-PDGFRA in bone marrow cells.     ///    " A novel oncogenic mutation (FIP1L1-PDGFRA), which results in a constitutively activated platelet-derived growth factor receptor-alpha (PDGFRA), has been invariably associated with a primary eosinophilic disorder. "    ///    Treatment with low-dose imatinib (100 mg/d) produced complete and durable responses in all 8 FIP1L1-PDGFRA(+) cases treated.     ///    "None of 8 patients with reactive eosinophilia displayed the abnormality, whereas the incidence of FIP1L1-PDGFRA in the remaining 81 patients with primary eosinophilia was 14% (11 patients). "    ///    FIP1L1-PDGFRA is a relatively infrequent but treatment-relevant mutation in primary eosinophilia that is indicative of an underlying systemic mastocytosis..     ///    The bone marrow mast cell infiltration pattern in FIP1L1-PDGFRA(+) SMCD-eos was distinctly diffuse with loose tumoral aggregates.     ///    FIP1L1-PDGFRA fusion: prevalence and clinicopathologic correlates in 89 consecutive patients with moderate to severe eosinophilia.. 