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

INTRODUCTION: 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. CASE PRESENTATION: 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. CONCLUSION: 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.