Eosinophilic myeloid neoplasms: an update

Abstract

This presentation which addresses changes and updates in eosinophilic disorders, is based on the recently published International Consensus Classification of myeloid neoplasms (Arber DA, Orazi A, Hasserjian RP, et al. Blood 2022; 140: 1200–1228). The previous category of myeloid/lymphoid neoplasm with eosinophilia (M/LN-eo) and a specific gene rearrangement is now changed to M/LN-eo with tyrosine kinase gene fusions to reflect the underlying genetic lesions. Two new members, M/LN-eo with ETV6::ABL1 fusion and M/LN-eo with various FLT3 fusions, have been added to the category; and M/LN-eo with PCM1::JAK2 and its genetic variants ETV6::JAK2 and BCR::JAK2 are recognised as a formal entity from their former provisional status. Our updated understanding of the clinical and molecular genetic features of PDGFRA, PDGFRB and FGFR1 neoplasms is summarised. Bone marrow morphology now constitutes one of the diagnostic criteria of chronic eosinophilic leukaemia, NOS (CEL, NOS), and idiopathic hypereosinophilia/hypereosinophilic syndrome (HE/HES), facilitating the separation of a true myeloid neoplasm with characteristic eosinophilic proliferation from those of unknown etiology and not attributable to a myeloid neoplasm. Reference 1. Tzankov A, Reichard KK, Hasserjian RP, Arber DA, Orazi A, Wang SA. Updates on eosinophilic disorders. Virchows Arch 2022; doi: 10.1007/s00428-022-03423-3. Epub ahead of print. PMID: 36214901.