While ZMYM2::FGFR1 positive patients frequently present with the combination of a T-cell lymphoma/T-ALL/mixed phenotype acute leukemia and eosinophilia, BCR::FGFR1 positive patients usually present with a MPN/CML-like phenotype but a much lower incidence of hypereosinophilia >1.5 × 109/l, in the literature overall only reported in 3/21 evaluable patients [11, 28–50]. This evidence concerns the gene FGFR1 and acute lymphoblastic leukemia.