Representative hematopathology findings of incidentally discovered Richter transformation. (A) Images of hematoxylin and eosin–stained slides for each case. Original magnification (OM) is listed in each panel. (B) Immunohistochemistry (IHC) demonstrating CD5-positive (top left panel) and CD23-positive (top right panel) large atypical lymphocytes, as well as a Ki-67 proliferation index of 80% to 90% (bottom left panel) and strongly positive programmed death 1 staining (bottom right panel) in case 2.