Neutrophilic leukocytosis is the initial major finding of CML, which is defined by the World Health Organization as a MPN that originates in an abnormal pluripotent bone marrow stem cell, with the BCR-ABL1 fusion gene found in all myeloid lineages, as well as in some lymphoid and endothelial cells [2, 3]. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.