Are Bone Marrow Monocyte Characteristics at Diagnosis Indicative of the Evolution of Myelodysplastic Neoplasms to Chronic Myelomonocytic Leukemia?
Year: 2026
Type: article
Study design: Observational Study
Abstract: Background The progression of myelodysplastic neoplasms (MDS) to chronic myelomonocytic leukemia (CMML) has been recognized since a long time. Several works have shown that 4.8% - 20% of patients with MDS may progress to CMML, depending on the criteria used to define CMML. As bone marrow (BM) immunophenotyping has been established as a useful ancillary method for the diagnosis of MDS, the question has been raised if some phenotypic characteristics of monocytes could predict this evolution in MDS patients. In a previous study of our group, analyzing the immunophenotypic features of BM in patients with MDS at diagnosis, 27% showed an increased percentage of monocytes compared to normal BM without peripheral monocytosis. This feature, together with increase of CD34+ myeloid progenitors and decrease of B-cell progenitors were associated with a poor outcome of the patients. Aim Our aim was to analyze in a long-term follow-up of these patients, the progression to CMML. Methods We examined patients of our Institution that were diagnosed between 2005 and 2012. Diagnosis was based on findings of peripheral blood cytopenias, BM cytology, cytogenetics and immunophenotyping with a 4-color flow cytometric protocol. Infinicyt 1.7 software was used for the analysis. WHO criteria were used for patients’ classification. Diagnosis of CMML was made when peripheral blood monocytes were persistently ≥ 1x109/l. Results Among 95 cases, 26 that had total monocytes / total nucleated cells in BM immunophenotyping above the normal range (> 5.5% in controls). Among them, 6 (23%) progressed to CMML during their evolution: median 6,3 months (2-29). The median time of observation of all patients was 59 months. In May 2026 only 23 patients were still alive, and those who progressed to CMML were all dead. At diagnosis, patients progressing to CMML had a higher percentage of total monocytes / TNC (median 9.5%) but the percentage of CD16+monocytes among total monocytes was very variable and there was no statistical difference between both groups. Age and percentage of BM CD34+ myeloid cells were also not different in both groups. BM B-cell progenitors were absent at diagnosis in all cases developing CMML. Conclusion Increase in BM monocytic lineage is frequent in MDS, although no monocytosis is detected in peripheral blood. However, it may be indicative of a progression to CMML. Our data also further confirm the existence of the entity oligomonocytic CMML recently included in the WHO and ICC classification. However, the evolution of MDS to full-blown CMML should be confirmed by molecular tests.
Language: English
Subfield: Hematology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7223130427