The finding of a significantly increase number of CREBBP alterations (p = 0.046, Mann–Whitney U test) in PCNSLs classified as “Other” compared to MCD might, thus, imply a small subset of PCNSL to more resemble GCB-like DLBCL or, alternatively, the existence of a group of occult systemic GCB-lymphomas with first clinical presentation in the CNS. Here, CREBBP is linked to diffuse large B-cell lymphoma.