The TdT‐positive DLBCL/HGBCL‐MYC/BCL2 group was characterised by the mutation signature associated with FL (BCL2, KMT2D, CREBBP, TNFRSF14), and those associated with high‐grade transformation (MYC, TP53, CCND3, PIM1, B2M, DDX3X, S1PR2). Here, CREBBP is linked to diffuse large B-cell lymphoma.