Morphological differences in monocytes from chronic myelomonocytic leukemia and reactive monocytosis 2449

Abstract Description Chronic myelomonocytic leukemia (CMML) is considered to be a chronic myelodysplastic and myeloproliferative neoplasm characterized by a persistent increase in abnormal monocytes. According to the 2022 WHO classification,CMML is defined when 94% and more CD14+CD16- cells are detected in monocytes by flow cytometry. However more than 90% of those cells are also detected in patients with reactive monocytosis (RM), this makes the differentiation of CMML from RM difficult. We investigated the differences in cell morphology and compared the values ??of monocyte parameters side fluorescence (SFL) obtained by flow cytometry between both diseases. In this study, five patients with CMML and 44 patients with RM were enrolled. In morphological comparison of monocytes, the size of monocytes from patients with RM (20.39 ± 2.24 mm) was significantly bigger than that from CMML (17.25 ± 1.02 mm). When comparing the number of vacuoles over 1.0 mm, 3.3 ± 1.0 vacuoles were detected in monocytes from patients with RM and 1.0 ± 0.3 vacuoles were detected in monocytes from CMML. When the mean gray values of monocytes were examined, values of monocytes from RM (156.1 ± 3.7) were significantly higher than those from CMML (145.9 ± 3.7). The median values of SFL in monocytes by flow cytometry were 103.4 ± 5.8 (RM) and 114.1 ± 4.6 (CMML), SFL in monocytes from CMML was significantly higher than that from RM. Morphological characteristics and SFL may be useful in the differentiation of CMML from RM. Funding Sources Supported by JSPS KAKANHI, JP 21K15645 Topic Categories Lymphocyte Differentiation and Peripheral Maintenance (LYM)