The current approach to the diagnosis of myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are heterogeneous hematopoietic neoplasms that share key clinical and biologic features, including peripheral blood cytopenias, morphologic dysplasia, ineffective and clonal hematopoiesis, and a variable risk of transformation to acute myeloid leukemia. Diagnostic evaluation of MDS relies on morphologic assessment of the peripheral blood and bone marrow, conventional cytogenetics, and exclusion of secondary causes of dysplasia. The diagnosis of MDS has important clinical consequences, but it can be challenging and requires distinction from mimics. In this review, the principles of bone marrow interpretation with respect to the diagnosis and classification of MDS in the current era will be discussed, including accurate morphologic interpretation, use of flow cytometry and immunohistochemistry, appropriate use of cytogenetics, and the emerging role of molecular genetics.