Comparison of genetic and clinical aspects in patients with acute myeloid leukemia and myelodysplastic syndromes all demonstrating more than 50% of bone marrow erythropoietic cells

Background. The World Health Organization separates acute erythroid leukemia (erythropoiesis in ≥50% of nucleated bone marrow cells; ≥20% myeloblasts of non-erythroid cells) from other entities with increased erythropoiesis–acute myeloid leukemia with myelodysplasia-related changes (≥20% myeloblasts of all nucleated cells) or myelodysplastic syndromes, and subdivides acute erythroid leukemia into erythroleukemia and pure erythroid leukemia subtypes. We aimed to investigate the biologic/genetic justification of the different categories for myeloid malignancies with increased erythropoiesis (≥50% of bone marrow cells). Design and Methods. We investigated 212 patients with acute myeloid leukemia or myelodysplastic syndromes (18.5-88.4 years) characterized by erythropoiesis ≥50%: 108 acute myeloid leukemia (77 acute erythroid leukemia–corresponding to erythroid/myeloid erythroleukemia); 7 pure erythroid leukemia; 24 acute myeloid leukemia with myelodysplasiarelated changes) and 104 myelodysplastic syndromes. Morphology and chromosome banding analysis was performed in all cases; subsets of cases were analyzed by polymerase chain reaction and immunophenotyping. Results. Unfavorable karyotypes were more frequent in acute myeloid leukemia than myelodysplastic syndromes (42.6% vs. 13.5%; p<0.0001), but did not differ significantly between acute erythroid leukemia (39.0%), pure erythroid leukemia (57.1%), and AML-MRC (50.0%). Molecular mutations did not differ significantly between the different categories. The 2-year overall survival rate was better in myelodysplastic syndromes than acute myeloid leukemia (p<0.0001), without significant differences across the different acute leukemia subtypes. 2-year overall survival rates were worse in unfavorable than intermediate karyotypes (p<0.0001). In multivariate analysis, myelodysplastic syndromes versus acute myeloid leukemia (p=0.021) and cytogenetic risk category (p=0.002) only were significant. Conclusions. Separation of acute myeloid leukemia and myelodysplastic syndromes with ≥50% of erythropoietic cells has clinical relevance, but it might be discussed to replace subclassification into different acute erythroid leukemia subtypes or as acute myeloid leukemia with myelodysplasia-related changes by acute myeloid leukemia with increased erythropoiesis ≥50%.