Erythroleukemia: a comparison between the previous FAB approach and the WHO classification.

Erythroleukemia is, within FAB classification, a proliferation of erythroblasts superior to 50% and of myeloblasts superior to 30%. The new WHO classification abolishes the frontier between RAEB-t with 20% and leukemia with 30% of blasts. AML6 variant is a new entity characterized by the proliferation of immature erythroblasts and the absence of non-erythroid blast cells. We analyzed 16 erythroleukemia, 5 RAEB-t and 2 AML6 variants to clarify their relationship. We suggest on survival, karyotype and cytologic characteristics that secondary erythroleukemia are the same entity as RAEB-t, confirming the WHO classification and that amongst de novo erythroleukemia, there is 'AML6 variant' with pure erythroid lineage proliferation.