C1 (18% of DLBCL) has cases with BCL6 chromosomal translocations, active NOTCH signaling (NOTCH2 mutations, SPEN inactivation), active NF-κB pathway (TNFAIP3 mutations or deletions, BCL10 mutations), and immune escape mechanisms (inactivation of CD70, CD58, FAS, and structural variations of PD-L1 and PD-L2). Here, SPEN is linked to diffuse large B-cell lymphoma.