A modern classification of the acute non-lymphoblastic leukaemias.

Acute leukaemias have traditionally been classified according to the nature of the predominating cells as judged by cytomorphology and cytochemistry. A codification of this classification into M1-M7 for myeloid cases (AML), proposed by the FAB group of haematologists, has been used extensively in the past decade. Some criticisms of this codification are presented and other approaches to classification are discussed. Among these are included the potential importance of multiple lineage expression, measurements of cell differentiation using cytochemical criteria, surface antigenic differences as demonstrated by the use of monoclonal antibodies and the growing contribution of cytogenetics. A simplified classification into broad groups is proposed. These groups may be further elaborated as appropriate.