AML M1 – Acute Myeloid Leukaemia without Maturation

AML M1 or acute myeloblastic leukemia without maturation, is characterized by a high percentage of bone marrow blasts (>20%) with­out significant evidence of maturation along the granulocytic series.

Diagnostic Criteria (WHO 2016)

• Maturing cells of the granulocytic lineage constitute < 10% of the nucleated bone marrow
• Myeloid nature of the blasts is demonstrated by positivity for MPO or Sudan Black B staining (in ≥3% of blasts) and/or the presence of Auer rods
• AML without maturation does not fulfil the criteria for inclusion in any of the previ­ously described groups

Blood Film Features:

• Leucocytosis with myeloblast
• Thrombocytopenia

Bone Marrow Features:

• Bone marrow is usually hypercellular
• Myeloblast with azurophilic granules +/- Auer rods
• Cytochemistry: MPO and sudan black positive

Other Resources

• ASH image bank: Acute myeloid leukemia NOS, acute myeloid leukaemia without maturation
• Clinical Flow Wiki: AML-M1