Myeloproliferative Disorders and Myelodysplastic Syndromes

The myeloproliferative disorders (MPD) and myelodysplastic syndromes (MDS) encompass a pathologically and clinically heterogeneous group of hematologic entities that are united by their putative origin from pluripotent hematopoietic stem cells. The World Health Organization classifies these entities into three broad categories: (1) the chronic myeloproliferative diseases, (2) the myelodysplastic syndromes, and (3) the myelodysplastic/myeloproliferative diseases1 (see Table 35-1). Though all are true hematopoietic stem cell disorders characteristically associated with bone marrow hyperplasia, they are divergent in that MPD typically are associated with effective hematopoiesis, while MDS are associated with ineffective hematopoiesis, reflected by high or low peripheral blood counts, respectively.