Bone marrow aspiration biopsy (hematoxylin and eosin stain, ×10 magnification) at diagnosis (A) and (B). These images show cells losing normal staining characteristics, as well as coagulative necrosis of marrow elements and bony trabeculae. The red arrow shows the area of necrosis. Necrosis of the myeloid tissue on a background of amorphous eosinophilic material is shown. (C) and (D) Images obtained at the time of relapse show infiltration of the bone marrow by malignant mononuclear cells.