Myelodysplastic syndromes: diagnosis and staging.

Myelodysplastic syndromes (MDS) represent a heterogeneous group of hematologic disorders characterized by ineffective hematopoiesis and an increased risk of developing acute myelogenous leukemia (AML). Accurate diagnosis of MDS can be difficult, and its classification requires evaluation of cytopenias, bone marrow morphology, blast percentage, and cytogenetics. These factors, as well as patient performance status and red blood cell transfusion dependence, can be used to predict prognosis in MDS. Accurate diagnosis and classification are essential for subgroup identification and prognostic assessment of patients with MDS. This article reviews essential criteria for staging and subgroup classification and summarizes prognostic scoring systems that aid in risk stratification and selection of optimal therapy. Classification systems such as the World Health Organization (WHO) classification are widely used but do not always provide sufficient prognostic information. This limitation led to the creation of the International Prognostic Scoring System (IPSS). However, this system was designed to be used only at diagnosis and may not be suitable for serial assessment of patients whose disease can evolve over time. The WHO classification-based prognostic scoring system (WPSS) permits dynamic estimation of survival and risk of AML transformation at multiple time points during the natural course of MDS. Prognostic scoring systems such as WPSS allow for prediction of survival and risk of leukemic evolution at any time during the course of the disease. Such an approach may provide a useful adjunct for clinical decision making, including selection of appropriate treatment options.