BCR and diffuse large B-cell lymphoma: PIM1 mutations are prognostic in DLBCL,28 associated with the clinically aggressive MCD genetic subtype6, 25 frequent in ABC‐DLBCL, and associated with active BCR signaling (MYD88mut, CD79Bmut, gain of SPIB, gain of REL), cell‐cycle regulation (del‐CDKN2A, del‐PRDM1, ZFHX3) and apoptosis (gain‐BCL2).18