APL - Slide 2

An acute promyelocytic leukemia is an aggressive form of an acute myeloid leukemia. Usually, promyelocytes stand out due to an abundant amount of granules. There are however, variant forms in which these granules are lacking. In this slide, the presence of auer rods and faggot cells are the most important indicators of an APL. The diagnosis is confirmed by flowcytometry and molecular analysis (t(15;17)).

Blasts

Promyelocytes

Myelocytes

Metamyelocytes

Neutrophils

Lymphocytes

Monocytes

Erythroblasts

Immunophenotype

CD34-

CD117±

HLA-DR-

CD13+

CD33++

CD2-

The promyelocytes have a high side-scatter and are CD34-, CD117+ and HLA-DR-. The expression of CD13 is heterogenous and there is a strong, homogenous expression of CD33. The hypogranular variant of APL is usually CD34+ and CD2+.

SSC

CD45

CD117

CD34

HLA-DR

CD13

CD16

CD14

CD33

Neutrophils

Promyelocytes