Philadelphia-positive BCR-ABL+ chronic myeloid leukaemia (CML) classically presents peripheral neutrophilia, basophilia, and eosinophilia; in rare cases the disease presents with prominent hypereosinophilia, as the eosinophilic variant of CML (eoCML). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.