Cytomorphology. Left panel: Bone marrow aspirate of case 1 before treatment of lenalidomide. Right panel: bone marrow aspirate of case 1 after treatment of lenalidomide. The May-Grünwald-Giemsa staining (top) illustrates the disappearance of atypical megakaryocytes with large hyperlobulated nuclei; the iron staining (bottom) illustrates the disappearance of ring sideroblasts after treatment with lenalidomide. A Leica DMLB2 microscope with a Leica DC500 camera and DC TWAIN software was used to make the photograph (40× and 100× objectives).