Cytochemical staining and flow cytometry methods applied to the diagnosis of acute leukemia in the pediatric population: An assessment of relative usefulness

Background: Cytochemical staining has been used in the diagnosis of acute l eukemia for more than 20 years. The general availability of flow cytometers and an extensive panel of antibody reagents useful for characterizing bloo d cell lineage question the usefulness of continuing routine use of the cyt ochemical staining for the diagnosis of acute leukemia. Patients and Methods: Test results were evaluated in 122 (n = 122; 112 with acute lymphocytic leukemia and 10 with acute myeloid leukemia) patients se lected from among 320 patients with acute leukemia at Texas Children's Hosp ital in 1997 and 1998 Results were selected for review if the clinical enco unter represented the initial diagnostic work-up and if data were available from cytochemical staining and flow cytometry studies. Results: Cell lineage classification derived from flow cytometry and cytoch emical stains were in agreement in all cases. Definitive diagnoses were fea sible using flow cytometry results alone in 120 of 122 patients (98.4%) as compared with only 99 of 122 patients (81.2%) when only cytochemical staini ng results were considered. In two patients with inconclusive flow cytometr y results, cytochemical staining alone provided information sufficient for diagnosis. Conclusions: Results from this study indicate that with few exceptions, flo w cytometry studies alone provide sufficient information for diagnosis and management of acute leukemia in children. Nevertheless, cytochemical staini ng should be available for those cases in which flow cytometry results fail to allow a definitive diagnosis. A modified testing protocol is recommende d.