Anemia as the Main Manifestation of Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a constellation of different diseases sharing anemia in the great majority of cases, and this cytopenia defines these pathologies and their most dramatic clinical manifestations. Anemia in MDS is due to ineffective erythropoiesis, with a high degree of apoptosis of marrow erythroid progenitors. These progenitors show distinctive dysplastic features that consent diagnosis, and are recognizable and differentiated, although not easily, from other morphologic alterations present in other types of anemia. Reaching the diagnosis of MDS in a macrocytic anemia and alleviating the symptoms of anemia are therefore an essential objective of the treating physician. In this work, the signs and symptoms of anemia in MDS, as well as its peculiar pathophysiology, are discussed. Erythopoietic stimulating agents (ESAs) are providing the best treatment for anemic MDS patients, but their use is still not approved by health agencies. While still waiting for this waiver, their clinical use is widespread and their effectivness is well known, as well as the dismal prognosis of patients who do not respond to ESAs and require transfusions. MDS with del5q constitute a unique model of anemia whose complex pathophysiology has been clarified at least partially, defining its link to ribosomal alterations likewise what observed in hereditary anemias like Blackfan Diamond anemia. Lenalidomide is the agent that has shown striking and specific erythropoietic activity in del5q MDS, and the basis of this response is starting to be understood. Several new agents are under evaluation for ESA refractory/relapsed MDS patients, targeting different putative mechanisms of ineffective erythropoiesis, and are here reviewed.