The patient is a 22-year-old Hispanic male with HIV/AIDS who presented with fever and decreasing platelet count. A bone marrow biopsy showed a large number of atypical megakaryocytes (see arrows) with condensed nuclear lobation ("mummified" megakaryocytes). Normal appearing megakaryocytes are also noted. There were no dysplastic features to the erythroid or myeloid elements. Cytogenetics showed normal male karyotype.