What are myelodysplasias?

Group of clonal disorders of hematopoietic stem cells, characterized by bone marrow failure in association w/dysplastic changes in one or more cell lineages. Bone marrow is overactive (ineffective EPO) w/peripheral cytopenia Pathogenesis (May precede AML, tends to occur in older individuals especially common in those treated w/prior chemotherapy Presents w/ pancytopenia, shift to immaturity in granulocytes <20% blasts, dysplasia in one or more lineages