Pathologic aspects of the lymph node in the CLL phase and in the DLBCL phase from a patient who experienced clonally related RS transformation. Hematoxylin and eosin sections of CLL involved lymph node (A) and of DLBCL-type Richter transformation (B). The expression of CD20, CD5, CD23, and Ki67 detected by standard immunohistochemistry, the CLL-phase lymph node (C, E, G, I), and, for comparative purposes, in the DLBCL-type Richter transformation (D, F, H, J), are shown. Original magnification ×20 for all panels.