The GCB DLBCL C4 (17% of all DLBCL) contains cases with genetic lesions affecting chromatin structure (mutations in linker and core histone genes), immune escape (CD83, CD58, and CD70), NF-κB pathway (mutations of CARD11, NFKBIE, and NFKBIA), BCR and PI3K signaling (mutations of RHOA and SGK1), cell motility (GNA13 mutations), and RAS/JAK/STAT signaling (BRAF and STAT3 mutations). The gene discussed is BRAF; the disease is diffuse large B-cell lymphoma.