Usefulness of the lymphocyte positional parameters in the Sysmex XN haematology analyser in lymphoproliferative disorders and mononucleosis syndrome.

INTRODUCTION

The lymphocyte positional parameters included in Sysmex XN have been suggested as useful means to differentiate lymphoproliferative disorders (LPD), mononucleosis syndrome (MNS) and other lymphocytoses.

METHODS

We evaluated Sysmex XN analysers, which supply 6 lymphocyte positional parameters that can be measured in the WDF scattergram: LY-X, LY-Y, LY-Z, LY-WX, LY-WY and LY-WZ.

RESULTS

We collected 301 samples from normal controls, polyclonal lymphocytosis, MNS and LPD. MNS and monoclonal expansion of T granular lymphocyte (T-GL) diagnostic groups accumulated higher numbers of significant differences in the mean values in comparison with the other groups. We propose a new algorithm that can differentiate T-GL cases from other diagnostic groups with an SE of 67.5%, an SP of 98.2%, a PPV of 87.1% and an NPV of 94.3%. Another algorithm showed its efficiency to differentiate MNS cases from other diagnostic groups with an SE of 63.6%, an SP of 97.5%, a PPV of 70.0% and an NPV of 96.7%. In 38.5% of all cases, the analyser did not generate any morphologic flag. Abnormal results in lymphocyte positional parameters were useful to detect 72.5% of these samples.

CONCLUSION

The lymphocyte positional parameters provided by Sysmex XN analysers are useful to differentiate expansions of T-GLs from other LPD and to differentiate MNS cases from other diagnostic groups. In addition, these parameters are very useful for detecting changes in the lymphocytes that make it necessary to review blood smears in samples without morphological flagging.