Dysplastic megakaryocytes in bone marrow biopsy from NPM1-mutated AML. (Top left) Infiltration by myeloid blasts (double arrows) admixed with dysplastic, monolobated megakaryocytes (single arrows; paraffin sections; hematoxylin-eosin. (Top right) Myeloid blasts as well as a monolobated megakaryocyte (single arrow) are CD34⁻. CD34⁺ small vessels serve as positive control. (Bottom left) Myeloid blasts (double arrows) and a dysplastic monolobated megakaryocyte (single arrow) show aberrant cytoplasmic expression of NPM. (Bottom right) Myeloid blasts (double arrows) and a dysplastic monolobated megakaryocyte (single arrow) show nucleus-restricted expression of nucleolin/C23. Immunostainings for CD34, NPM, and C23 were shown with the APAAP technique (hematoxylin counterstaining). All images were collected using an Olympus B61 microscope and a Plan Fl 100×/1.3 NA oil objective; Camedia 4040, Dp_soft Version 3.2; and Adobe Photoshop 7.0.