The GCB subtype is CCD10+ or BCL-6+, CD10-, and IRF4/MUM1-, while the non-GCB subtype is CD10- or IRF4/MUM1+ [38]. The Ki-67 index is higher in DLBCL compared to indolent lymphoma due to how it correlates with the degree of aggressiveness of the lymphoma (Figure 4) [6,39]. Here, IRF4 is linked to diffuse large B-cell lymphoma.