Hypocellular Myelodysplastic Syndrome: Relationship to Aplastic Anemia and Hypocellular Acute Myeloid Leukemia

The myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are usually manifest by a bone marrow that is normocellular or hypercellular, consisting of abnormally proliferating hematopoietic clones (1,2). In contrast, aplastic anemia (AA) is characterized by hypocellular marrow, and hematopoiesis in AA is usually polyclonal (though occasionally it can be oligoclonal or even monoclonal).