Bone marrow characteristics of patients with chronic myelomonocytic leukemia at the National Institute of Hematology and Blood Transfusion

Abstract

Objective: To describe bone marrow histopathological characteristics in patients with chronic myelomonocytic leukemia (CMML). Subjects and methods: A crosssectional study was conducted on 58 newly diagnosed CMML patients at the National Institute of Hematology and Blood Transfusion from January 2020 to December 2024, aged ≥16 years. All samples were stained with hematoxylin and eosin (H&E) and classified according to the WHO 2016 standard. Results: The mean age was 65.43 years, with the 61-75 age group accounting for the highest proportion (53.5%); the male-to-female ratio was 2.41:1. Bone marrow was predominantly hypercellular (98.3%), with uneven cellular distribution (41.4%) and architectural alterations of hematopoietic compartments (24.1%). The erythroid lineage was mainly hypoplastic (67.2%), whereas the granulocytic lineage remained largely within normal limits (53.4%). Dysplastic changes were identified across each line: erythroid cells (62.1%), granulocytes (82.8%), and megakaryocytes (74.1%). Meanulile, dysplasia involving two or more lineages accounted for 74.2% of all cases. Typical abnormalities included multinucleated erythroblasts with cytoplasmic abnormalities, hyposegmented granulocytes with abnormal granulation, and small megakaryocytes with round nuclei. Conclusions: Bone marrow histology in CMML is characterised by marked hypercellularity, multilineage dysplasia, and architectural alterations of hematopoietic compartments, reflecting the myelodysplastic-myeloproliferative nature of the disease. These findings provide additional histopathological data from a Vietnamese cohort for comparison with WHO-based classifications.