Historically, the diagnosis and classification of acute leukaemia involved morphologic review of blasts in the peripheral blood and bone marrow smears and cytochemical staining. Cytochemical stains, which are enzymatic colorimetric reactions that occur in the cells of interest, were necessary to assign and confirm myeloid and lymphoid lineage. In the current WHO 2008 Classification of leukaemia, immunophenotyping and cytogenetic analysis have largely replaced cytochemical staining in the characterization of acute leukaemia. Nonetheless, cytochemical testing remains a useful adjunct assay for the proper classification of acute leukaemia in a number of diagnostic settings.
Saha et al. (2025) studied this question.