This category name has changed from the previous “myeloid/lymphoid neoplasms with eosinophilia and rearrangement of PDGFRA, PDGFRB or FGFR1, or with PCM1::JAK2” (MLN-eo) [3], to specify the underlying molecular genetic changes and to include cases with ETV6::ABL1, FLT3 fusions or other TK fusion genes. The gene discussed is JAK2; the disease is lymphoid neoplasm.