AN ASSESSMENT OF THE COULTER VCS AUTOMATED DIFFERENTIAL COUNTER SCATTERPLOTS IN THE RECOGNITION OF SPECIFIC ACUTE-LEUKEMIA VARIANTS

The Coulter VCS is an automated differential counter, which derives a five-part differential count on the basis of differences in cell volum e, high frequency conductivity and light scatter. A printed scatterplo t relating volume and scatter is readily obtained. Other instruments w hich use automated cytochemistry can distinguish between AML and ALL, and between AML variants. It was our impression that the Coulter VCS m ight also be capable of such distinction on the basis of the scatterpl ot patterns, We therefore collected scatterplots produced by Coulter V CS analysis of peripheral blood from 63 patients presenting with acute leukaemia. The scatterplots were inspected and six basic patterns ide ntified. The scatterplots could be reproducibly sorted into pattern-sp ecific groups without knowledge of the diagnosis. Precise leukaemic di agnoses were made routinely: by conventional morphology, cytochemistry and immunophenotyping. A comparison was then made with the scatterplo t patterns. The 51 cases of AML produced examples of all six patterns. The nine cases of ALL produced only three patterns, These were shared with cases of AML, and two were also shared with the three cases of a cute mixed lineage leukaemia. Thus, three of the six patterns were spe cific for AML, whereas no pattern was specific for ALL or acute mixed lineage acute leukaemia. One pattern was produced only by the three ca ses of AML M6, and another was produced only by five of the 25 cases o f primitive (M0 and M1) AML. All 15 cases of AML M4 and M5 produced on e of two related patterns. These were shared with other AML variants, and one was also shared with ALL. In cc,nclusion, analysis of the Coul ter VCS scatterplots was capable, in the case of some patterns, of dis tinguishing between AML and ALL, and between some AML variants.