AML without maturation

At least 20% medium-sized blasts in blood or bone marrow with a round or slightly indented nuclei with dispersed chromatin, one or two nucleoli, varying degree of basophilic cytoplasm. Some azurophilic granulation and/or Auer rods may be present.
The blasts are Sudan Black (partly) positive (>3%), usually express CD13, CD33, MPO (>3%) and CD117.