Myeloid and lymphoid neoplasms with eosinophilia and PDGFRA rearrangements are recognized as a distinct entity within the section of “Myeloid/Lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK)”. Based on the WHO classification of tumors of Hematopoietic and Lymphoid tissues (5th Ed, 2022), these neoplasms also comprise of PDGFRB rearrangement, FGFR1 gene rearrangements, JAK2 rearrangement, FLT3 rearrangement, ETV6::ABL1 fusion as well as some others. Of note, these are recently defined entities and are still evolving. In this chapter, practical issues regarding diagnosis, cytogenetic testing, molecular studies, therapeutics, and clinical implications are discussed. Differential diagnosis in consideration for eosinophilia and hypereosinophilic syndrome are further highlighted.
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