JAK2 and chronic myelogenous leukemia, BCR-ABL1 positive: The subtle morphologic diagnosis and differentiation between coexisting JAK2 V617Fpos MPN and BCR::ABL1pos CML is complicated by the fact that left-shifted leukocytosis, thrombocytosis, BM hypercellularity and myelofibrosis can variably occur in both entities.