Rearrangements of FGFR1 are associated with a heterogeneous set of hematological malignancies thought to be derived from a pluripotent haematopoietic stem cell that may present as an atypical myeloproliferative neoplasm, a lymphoblastic lymphoma, or in transformation to either a myeloid or lymphoid acute leukemia in which eosinophilia is characteristic but not invariable [2]. Here, FGFR1 is linked to myeloproliferative neoplasm.