Acute Erythroblastic Leukemia (M6)

Erythroleukemia

• Acute erythroleukemia is characterized by an abnormal proliferation of erythroid and myeloid precursors. These patients have hypercelluar bone marrow with marked erythroid hyperplasia.
  
  
• Megablastoid changes can be seen in the erythroblasts along with other dysplastic features, including bizarre multinucelation, markedly vacuolated cytoplasm of erythroblast, and cytoplasmic budding.
  
  
• Positive PAS staining of the erythroblasts is consistent with, but not specific for, the diagnosis of erythroleukemia. Negative staining does not rule it out.
  
  
• Myeloblasts and promyelocytes are present in increased numbers (<30 % of nonerythroid cells).
  
  
• Uer rods may be present.
  
  
• Abnormal megakaryocytes may also be present.
  
  
• Erythroleukemia has three sequential morphologically defined phases in which the size of the myeloid component varies. 1) Erythremic myelosis, in which there is a preponderance of abnormal erythroblasts; 2) erythroleukemia, in which an increase in erythroblasts and in myeloblasts is seen; 3) myeloblastic leukemia.
  
  
• It is well recognized that many patients who are diagnosed with erythroleukemia will have their disease evolve into a leukemic stage indistinguishable from AML M1, M2, or M4 type.
  
  
• Anemia is present often more so than in other forms of AML.
  
  
• Lack of significant increase in reticulocytes is common and is due to ineffective erythropoieses.
  
  
• PB frequently nucleated red blood cells (NRBC) and myeloblasts are present but it is possible to see patients who are anerythremic or aleukemic, or both.
  
  

PROGNOSIS

May terminate in AML (M1 or M2) or AMML (M4)
usually 5 years