Usefulness of high‐fluorescence body fluid cell count (HF‐BF %) in Automated hematology analyzer SYSMEX XN‐350 for screening abnormal cells in body fluid analysis

Background Automated hematology analyzer Sysmex XN‐350 is operated by two analytical software, whole blood‐mode and body fluid mode. The body fluid mode can be counted the cells twice as many as than whole blood mode and it is suitable for body fluid analysis which the sample has low cell count. XN‐350 is calculated the cell counts including total nucleated cell, WBC, RBC, mononuclear(MN) cell, polymorphonuclea(PMN) leukocyte and differentiated MN%, PMN%, high‐fluorescence body fluid cell(HF‐BF)%. The cell types in HF‐BF are macrophages, mesothelial cells, synovial cells and other abnormal cells. Higher HF‐BF% means higher abnormal cells. We evaluated the correlation HF‐BF % by XN‐350 to microscopic examination. Methods Five hundreds twelve body fluid samples enrolled in this study. All samples analyzed HF‐BF % by XN‐350 instrument and the results compared to microscopic examination. In preliminary study, fifty‐two body fluid samples analyzed by XN‐350. Twelve samples in all samples revealed less than 1% HF‐BF and they were all normal cells by microscopy, and then we decided the cut‐off level for manual slide review was above 1.0% HF‐BF. We analyzed abnormal cell detection rate according to HF‐BF %. Results In five hundreds twelve samples, two hundreds eighteen samples(42.6%) were less than 1% HF‐BF and two hundreds nighty‐four samples(57.4%) were more than 1% HF‐BF. Twenty‐seven samples in more than 1% HF‐BF were detected clinically significant abnormal cells by microscopy. In according to the grade of HF‐BF %, 1.0~4.9% HF‐BF was one hundred thirty‐two samples including three samples(2.3%) that detected abnormal cells by microscopy, 5.0~9.9% HF‐BF was fifty‐one samples including six samples(11.8%) that detected abnormal cells by microscopy, 10.0~19.9% HF‐BF was fifty‐eight samples including six samples(10.3%) that detected abnormal cells by microscopy, more than 20.0% HF‐BF was fifty‐three samples including twelve samples that detected abnormal cells by microscopy. Therefore, higher HF‐BF % assumed higher detection rate of abnormal cells by microscopy. Conclusion HF‐BF % in SYSMEX XN‐350 instrument is useful for screening of abnormal cells in body fluid analysis. Cut‐off level of above 1% HF‐BF can be detected majority abnormal cells and decreased microscopic examination rate.