Figure 1. Bone marrow biopsy revealing persistent CLL with transformation to DLBCL. (a) Peripheral blood cells contained “blastoid” appear to be large lymphocytes with moderate amounts of cytoplasm and irregular nuclei (× 200). (b) The cells have large, irregularly shaped nuclei with fine nuclear chromatin, and prominent nucleoli (× 400. (c) The bone marrow biopsy shows an interstitial infiltrate of small to medium sized lymphocytes (× 200. (d) PAX-5 immunostain of the marrow biopsy highlights the interstitial infiltrate (× 200). CLL: chronic lymphocytic leukemia; DLBCL: diffuse large B-cell lymphoma.