Classification of acute leukaemias

Area of Science:

• Hematology
• Oncology
• Cell Biology

Background:

• Traditional acute leukaemia classification relies on cytomorphology and cytochemistry.
• The FAB (French-American-British) L1-L3 (ALL) and M1-M7 (AML) system has been widely used.
• Criticisms of the FAB system highlight the need for more comprehensive classification methods.

Purpose of the Study:

• To critically evaluate the existing FAB classification for acute leukaemias.
• To explore novel approaches for leukaemia classification, including multiple lineage expression, cell differentiation markers, isoenzyme biochemistry, and cytogenetics.
• To propose a simplified, yet adaptable, classification system for acute leukaemias.

Main Methods:

• Review and critique of the FAB classification system.
• Discussion of emerging classification criteria: multiple lineage expression, cytochemical differentiation, isoenzyme analysis, immunophenotyping with monoclonal antibodies, and cytogenetics.
• Illustration of complex, combined classification systems.
• Proposal of a simplified classification framework.

Main Results:

• The FAB classification, while historically significant, presents limitations in accurately categorizing all acute leukaemias.
• Multiple biological features, including surface antigens, cytogenetics, and cell differentiation markers, offer valuable insights beyond traditional morphology.
• A simplified classification is proposed, stratifying ALL by antigenic and cytogenetic profiles, and AML by morphology and cytochemistry.

Conclusions:

• The traditional FAB classification requires augmentation with newer biological data for precise acute leukaemia categorization.
• A refined classification integrating immunophenotyping and cytogenetics for ALL, and morphology/cytochemistry for AML, offers a more robust approach.
• The proposed simplified classification provides a flexible framework for further elaboration and clinical application in acute leukaemia diagnosis and management.