Cell Volume Studies in B‐Cell Leukaemia

Summary Leucocyte volume histograms were obtained in 12 cases of B‐chronic lymphocytic leukaemia (B‐CLL), two cases of B‐prolymphocytic leukaemia (B‐PLL) and two cases of hairy‐cell leukaemia (HCL) by means of a Coulter model ZB1 linked to a channelyser. Visual examination of the histograms showed differences between the cases which were confirmed by measurement of the modal volume (MV) and the σ value (SD of log‐volume). The MV of the cells in B‐CLL ranged from 153·8 to 244·2 fl (mean 198·24 fl) and was lower than the MV in the cases of HCL (427·5 and 465·6 fl). One case of B‐PLL had cells with an MV within the B‐CLL range while in the other the MV was greater (317·9 fl). The histogram in one of two cases of B‐CLL in ‘prolymphocytoid’ transformation showed a relatively high σ value, thus suggesting heterogeneity in cell size. The volume histogram is a simple method of sizing the predominant cell in the peripheral blood in lymphoproliferative disorders and permits an objective comparison between cell sizes in different diseases.