Interobserver Variability with the Diagnosis of Acute Myeloid Leukemia (AML) and Myelodysplastic Syndrome (MDS) Is the Threshold of 20% Bone Marrow Blasts Reproducible?

Introduction. The boundaries between MDS and AML are still a matter of debate. In the 2001 WHO Classification, the myeloblast count distinguishing AML and MDS was lowered from 30% to 20% of the bone marrow (BM) cells or peripheral blood (PB) leukocytes. It was justified on the basis that treating patients with 20-29% BM blasts with intensive chemotherapy showed a similar outcome to those with > 30% BM blasts.