CD10 expression is more frequent insystemic DLBCL; therefore, CD10 positivity in a CNS DLBCL should prompt a search forsystemic DLBCL that has disseminated to the CNS.14 DLBCL in other locations is often subdivided in germinal center B-cell (GCB)or non-germinal center B-cell subtypes, according to expression of CD10, BCL-6, andMUM1.16,17 The GCB phenotype is associated with a better outcome whencompared with the non-GCB subtype.18 However, this association has not been confirmed in PCNSL. This evidence concerns the gene BCL6 and diffuse large B-cell lymphoma.