Performance of the XN-2000 WPC channel-flagging to differentiate reactive and neoplastic leukocytosis

BACKGROUND: The distinction between reactive and neoplastic leukocytes, especially atypical lymphocytes suspected to be reactive or neoplastic, is a particular challenge in automated hematological cell differentiation. The aim of the study was to evaluate the performance of the XN analyzer supplemented with the WPC channel for differentiating between reactive and neoplastic leukocytosis. METHODS: Blood samples of 253 patients with viral infections, lymphoma or leukemia were analyzed by the Sysmex XN-2000 analyzer equipped with the WPC channel. The results were compared to routine leukocyte differentiation using the routine Sysmex XE-2100 analyzer and automated digital microscopy (DM96). The combined information from standard morphology, immune phenotyping and clinical diagnosis served as a reference. RESULTS: The XN WPC channel demonstrated an excellent performance for differentiating neoplastic (AUC=0.933) and reactive leukocytosis (AUC=0.900) as compared to morphological smear examination (AUC=0.949 and AUC=0.968, respectively) or to the differentiation results of our routine hematology analyzer (AUC=0.630 and AUC=0.635, respectively). CONCLUSIONS: Our data show that the combined WDF/WPC of the Sysmex XN-Series analyzer is advantageous in the automated differentiation of neoplastic and reactive leukocytosis, thus supporting the correct diagnostic decision in the daily laboratory routine.