Flow Cytometric Bone Marrow Evaluation in Suspected Myelodysplastic Neoplasms

Myelodysplastic neoplasms (MDS) are acquired heterogeneous clonal hematopoietic stem cell neoplasms, clinically characterized by progressively ineffective hematopoiesis and an increased risk of acute myeloid leukemia. MDS are accompanied by an inflammatory microenvironment and genome instability. Signs of dysplasia can occur in the erythroid, myeloid, monocytic, and megakaryocytic cell lineages and result in anemia, neutropenia, and thrombocytopenia. Multi-parameter flow cytometry can be used to detect aberrant antigen expression patterns typical of MDS, which correlate with cytomorphologically identified dysplasias and provide important information for diagnosis and prognosis. Characteristic findings include an increase in myeloid progenitor cells; aberrant myeloid and erythroid maturation; aberrant marker expression on progenitor cells, granulocytes, and monocytes, which corresponds to lineage infidelity, under-/overexpression, or asynchronous expression; and an increase in monocytes and progenitor cells in chronic myelomonocytic leukemia. The latter represents an independent disease entity with a similar phenotype. In addition, flow cytometry can rule out other causes of cytopenia, such as lymphoma, acute leukemias, paroxysmal nocturnal hemoglobinuria, or systemic mastocytosis with associated hematologic neoplasm. To analyze those features, the European LeukemiaNet recommends a set of markers together with important technical aspects. At least three distinct aberrations in at least two lineages are associated with a high likelihood of MDS. © 2025 Wiley Periodicals LLC. Basic Protocol: Flow cytometric bone marrow evaluation in suspected myelodysplastic neoplasms.