Complete Remission to Imatinib in a Myeloid Neoplasm with Basophilia and PRKG2::PDGFRA Gene Fusion: A Case Report.

The three most common myeloid/lymphoid neoplasms (MLN) with eosinophilia and tyrosine kinase gene fusions have rearrangements of the genes coding the alpha and beta subgroups of platelet-derived growth factor receptors (PDGFRA, PDGFRB) and fibroblast growth factor receptor one (FGFR1). The most common partner gene of PDGFRA rearrangement is FIP1L1. However, a few notable exceptions to this have been reported. In our report, we present the case of a patient with high symptom burden and peripheral blood basophilia who initially went undiagnosed. Then, an unusual PRKG2::PDGFRA translocation with next-generation sequencing panel was detected. Treatment with imatinib led to complete remission. We discuss the clinical presentation, review the literature, and comment on its pathogenesis. In patients with myeloproliferative features, the absence of peripheral blood eosinophilia does not rule out MLN with tyrosine kinase gene fusions. Next-generation sequencing panels that detect RNA fusions may help uncover cryptic or rare fusions. MLN with PDGFRA rearrangement responds well to imatinib.