Abstract: Objective　To investigate the variation principle of DIFF scatter diagram of Sysmex XE2100 hematology analyzer on abnormal lymphocyte.   Methods　A total of 40 samples with the percentages of abnormal lymphocyte >10% and <10% having DIFF scatter diagram obvious changes were observed, and the variation principle of DIFF scatter diagram was summarized. Results　The samples with abnormal lymphocyte had abnormal scatter diagram by Sysmex-XE2100 hematology analyzer. The 13 samples which mainly existed monocytoid atypical lymphocyte showed abnormally homogeneous scatter diagram described as ellipsoidal or oblong above the scatter diagram of monocyte. Among 27 samples which mainly mixed with plasmacytoid atypical lymphocyte and blast-like atypical lymphocyte, there were 19 samples′scatter diagram turning into greyish white and extended upward in the area of lymphocyte and monocyte on the DIFF channel, and the other 8 samples′scatter diagram showed that lymphocyte, monocyte and neutrophile granulocyte in their respective area, but the scatter increased and overlapped around these areas. Conclusions　With the prompt indication of abnormal lymphocyte by the analyzer, the DIFF scatter diagram of hematology analyzer with microscopy on blood smear could reduce the chances of misdiagnosis and misidentified cases.

Key words: Abnormal lymphocyte, Hematology analyzer, Scatter diagram