The FAB classification for acute myeloid leukaemia--is it outdated?

The purpose of a classification is not only to group diseases with the same biological characteristics, but also to get insight into the pathogenesis and to define subgroups with different prognoses and different therapeutic approaches. In acute leukaemias the classification now most widely used is the French-American-British (FAB) classification as proposed in 1976, which was based on morphology and cytochemistry [l]. The FAB group felt that discrimination of myeloblasts from lymphoblasts on morphological characteristics only was insufficient. For this reason they proposed to define the difference between acute myeloid leukaemia @ML) and acute lymphoblastic leukaemia (ALL) by the positivity or negativity respectively of the blasts for the myeloperoxidase (MPO) or Sudan B Black reaction. Within acute myeloid leukaemia 6 categories were discriminated (Ml-M61 by morphology and the use of o-naphthyl acetate esterase (ANAE) to discriminate monoblasts from myeloblasts [ 1,2]. Later, immunological markers were used to define