Diffuse large B-cell lymphoma, not otherwise specified, has two histological subtypes, namely, the germinal center subtype, which is often positive for CD10 and/or BCL6 and negative for MUM1, and the activated B-cell/non-germinal center-like subtype, which is negative for CD10, with or without BCL-6 expression with expression of typically expressing MUM1. This evidence concerns the gene BCL6 and diffuse large B-cell lymphoma.