Ariel S Kniss and Edmund K Waller
Myelodysplastic syndromes (MDS) are a collection of bone marrow disorders with abnormalities in the differentiation of erythroid, myeloid and megakaryocyte lineages. The diagnosis of MDS is based upon cytopenia in the peripheral blood and morphological abnormalities in red cells, myeloid cells or thrombocyte lineages in the blood and marrow. Higher-risk MDS is associated with the presence of clonal cytogenetic abnormalities and increased myeloblasts in the marrow. Here we describe a patient with low-risk MDS who presented with anemia and a marked anisocytosis of red blood cells, seen on a peripheral blood smear, without chromosomal aberrations or increased myeloblasts in the bone marrow. The pathogenesis of anisocytosis in the context of MDS is discussed.