EPO and chronic myelogenous leukemia, BCR-ABL1 positive: We therefore conclude based on the low erythropoietin level and the BCR-ABL1 positivity, supporting the monoclonality of red stem cells, as well as the excellent evolution of erythrocytosis under imatinib therapy, that polycythemia without a high number of neutrophils may also be a feature of CML.