AML M2 – Acute Myeloid Leukemia with Maturation

Acute myeloblastic leukemia with maturation is characterized by the presence of ≥ 20% blasts in the bone marrow or peripheral blood with evidence of maturation.

Diagnostic Criteria (WHO 2016)

• ≥20% blasts in the bone marrow or peripheral blood
• Evidence of maturation – ≥10% of maturing cells of granulocytic lineage
• Monocyte lineage <20% of bone marrow cells

Blood Film Features:

• Leucocytosis with myeloblast
• Thrombocytopenia

Bone Marrow Features:

• Bone marrow is usually hypercellular
• Myeloblast: commonly with auer rods and azurophilic granules
• Monocyte lineage < 20% of bone marrow cells

Blood film from a patient with acute myeloid leukaemia with maturation and a t(8;21) translocation. Note the presence of blasts with auer rods and maturing myeloid cells in the peripheral blood.

Bone marrow aspirate from a patient with AML t(8;21). Note the numerous eosinophilic myelocytes. This is AML M2-Eo (M2 with eosinophilia). The blasts have a peri-nuclear hoff, basophilic cytoplasm and azurophilic granules, which is characteristic of AML t(8;21). The blasts are expected to be dimly positive for CD19 on flow cytometry.

Other features to look for:

• Variable degrees of dysplasia
• Increased basophils and mast cells
• Eosinophil precursors – suggestive of M2Eo
• Blasts with a perinuclear hof, abundant basophilic cytoplasm with azurophilic granules – suggestive of acute myeloid leukaemia with t(8;21)(q22;q22.1)

Other Resources

• ASH image bank: Acute myeloid leukemia NOS, Acute myeloid leukaemia with maturation
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