Some immunoblastic DLBCL, particularly those derived from preterminally-differentiated post-CG B-cells (plasmablastic-, primary effusion- and ALK+ DLBCL), often do not express CD20, CD79a and BSAP, but express MUM1, VS38c, CD138, or immunoglobulin (Ig) heavy or light chains (Delecluse et al. 1997; Delsol et al. 1997; Gatter and Warnke, 2001; Carbone and Gloghini, 2005; Teruya-Feldstein, 2005; Savage, 2006). This evidence concerns the gene IRF4 and diffuse large B-cell lymphoma.