Clonal eosinophilia is associated with myeloid or lymphoid neoplasms harboring PDGFRA, PDGFRB, or FGFR1 rearrangements, Philadelphia-negative myeloproliferative neoplasms, acute myeloid leukaemia, and B- or T-lymphoblastic leukemia/lymphoma featuring marked eosinophilia. This evidence concerns the gene FGFR1 and lymphoid neoplasm.