CD34 and acute myeloid leukemia: Noteworthy, a higher PI of non-lymphoid CD34+ cells and NRBC were both associated with a significantly longer overall survival (OS) and decreased risk of AML transformation, even among patients within the low and intermediate-1 IPSS risk categories, the PI of NRBC emerging as the most powerful prognostic factor for both OS and progression-free survival in MDS, independently of the haemoglobin levels and other classical prognostic variables.