Cytochemical Staining.

Historically, the diagnosis and classification of acute leukemia 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 leukemia, immunophenotyping and cytogenetic analysis have largely replaced cytochemical staining in the characterization of acute leukemias.

Detection of leukemic lymphoblasts in CSF is instrument-dependent.

Staging and monitoring of pediatric acute lymphoblastic leukemia (ALL) includes examination of the cerebrospinal fluid (CSF). At our institution, we noted an increased incidence of low-level leukemic blasts in CSF samples from patients with ALL. This increase coincided with a conversion from the Shandon CytoSpin 4 (Thermo Fisher Scientific, Waltham, MA) to the Wescor Cytopro Rotor AC-060 (Wescor, Logan, UT).