PDGFRB and Increased total eosinophil count: Patients presenting with a clinical phenotype of CMML with eosinophilia should be assessed for the t(5;12)(q31-q32;p13), giving rise to the ETV6(TEL)-PDGFRB fusion oncogene.14 The association between monocytosis and PDGFRA rearrangements is uncommon.15