FAB Classification of AML-3
M4:
Acute
Myelomonocytic Leukemia
>30%
of marrow nucleated cells are blasts
When
M:E ratio >1 then >20% but <80% of non-erythroid
cells are monocytes
M4
if pb has >5.0 x 109/L monocytes
Moderate
eosinophilia in 4% of cases (M4Eo)
If
pb monocytes is <5.0 x 109/L then NSE must be positive in >20% of
blasts
Chromosome
16 inversion in M4Eo
CNS
involvement more likely in M4Eo
Better
remission rate in M4Eo