Acute Erythroid Leukemia: A Review

Acute erythroid leukemia is a rare form of acute myeloid leukemia. It accounts for <5% of all acute myeloid leukemia cases. According to the World Health Organization 2008  classification, it falls under the category of acute myeloid leukemia, not otherwise specified and is further divided into two subtypes: erythroid leukemia (erythroid/myeloid) and pure erythroid leukemia. Currently, erythroleukemia (erythroid/myeloid) is defined as 50% or more erythroid precursors and ≥20% blasts of the non-erythroid cells. By definition, pure erythroid leukemia is composed of ≥80% erythroid precursors. Acute erythroid leukemia is a diagnosis of exclusion and difficulty. This review discusses its differential diagnoses, which present with erythroid proliferation, such as myelodysplastic syndrome with erythroid proliferation, acute myeloid leukemia with myelodysplasia related changes, therapy related acute myeloid leukemia, myeloproliferative neoplasms with erythroblast transformation, acute myeloid leukemia with recurrent genetic abnormalities and other types of hematologic neoplasms. Additionally, reactive conditions such as erythropoietin treatment, vitamin B12 and folate deficiency, toxin exposure and congenital dyserythropoiesis should be excluded. As a result, the frequency of acute erythroid leukemia diagnosis has been reduced. Important adverse prognostic factors will be summarized, including presence of complex cytogenetic karyotype as the most important one. Additional larger studies are needed to better understand acute erythroid leukemia, with a focus on diagnostic tools, its heterogeneity and cytogenetic and molecular characteristics for potential therapeutic targets.