Lymph node from a patient with chronic lymphocytic leukemia (CLL) undergoing Richter transformation. The monotonous infiltrate of small lymphocytes on the left side, representing the pre-existing CLL, contrasts with the large B cells on the right, representing transformation to a diffuse large B cell lymphoma.
From: Warnke RA, Weiss LM, Chan JK, et al. Tumors of the lymph nodes and spleen. Atlas of tumor pathology (electronic fascicle), Third series, fascicle 14, 1995, Washington, DC. Armed Forces Institute of Pathology.