Key oncogenic pathways in DLBCL. The 2 major molecular subtypes of DLBCL are shown: the GCB and the ABC type. Both tumors arise from stages of differentiation reminiscent of germinal center B cells. The GCB subtype arises from centroblasts, whereas the ABC subtype arises from a plasmablastic cell just prior to germinal center exit. The main oncogenic pathways are listed, as well as the recurrent mutations, gains and losses of genetic material, and characteristic translocations that underlie these pathway perturbations. In bold are oncogenic mechanisms that are preferentially found in 1 molecular subtype. Cb, centroblast; Cc, centrocyte; Pb, plasmablast; Pc, plasma cell; DHIT, double-hit lymphoma; del, deletion; BCR, B-cell receptor.