Diffuse large B-cell lymphoma (DLBCL) is a heterogeneous disease. At the 20th Congress of the European Hematology Association (EHA), Christian Gisselbrecht, MD, of Paris Diderot University, Paris, France, explains the clinical significance of molecularly subtyping DLBCL as germinal center B-cell (GCB) or non-GCB (activated B cell-like).