The myelodysplastic syndromes: classification and prognosis.

Myelodysplastic syndrome is a neoplastic clonal stem cell disorder characterized clinically by bone marrow failure and a tendency to progress to acute myelogenous leukemia. Dysplasia is the pathologic hallmark. The French-American-British classification served as the gold standard for more than two decades. Under the auspice of the World Health Organization, more than 100 hematopathologists in a 3-year cumulative effort issued the new World Health Organization classification, which recognizes multilineage dysplasia. Refractory anemia with excess blasts is divided into two groups. Chronic myelomonocytic leukemia is reclassified under a separate category. Refractory anemia with excess blasts in the transformation group was omitted. Finally, 5q-syndrome is a new subgroup. In addition to the pathologic classification, various prognostic predictors were formatted into scoring systems. Bone marrow blast percentage, cytopenias, and cytogenetics are the backbone for those prognostic models. The International Prognostic Scoring System is a product of pooled data from previous scoring systems and a useful tool to predict survival and acute myelogenous leukemia evolution. This paper discusses the classification and prognosis of myelodysplastic syndromes and their evolution.