The patient is a 56 year old with relapsed refractory AML with underlying t(8;21). Shown are core biopsy H&E and a Wright-Giemsa stained marrow aspirate smear. 

t(8;21)(q22;q22) is the most frequently observed karyotypic abnormality associated with acute myeloid leukemia (AML), especially in FAB M2. t(8;21)AML shows high levels of CD34 and DR expression, with a prevalent positivity for CD19 and CD56 surface markers (both present in this case)

The translocation between chromosomes 8 and 21 (t(8;21)) leads to fusion of the AML1 gene (RUNX1) on chromosome 21 and the ETO (RUNX1T1) gene on chromosome 8. The t(8;21) abnormality is found in approximately 5% to 10% of all patients with AML and 10% to 20% of AML with maturation.

The WHO diagnostic criterion for AML is the presence of 20% or more blasts in the bone marrow. However, according to the WHO classification, bone marrow blasts of less than 20% should also be diagnosed and treated as AML, if associated with t(8;21) abnormality.