An open brain biopsy and surgical exeresis of the right frontal lesion confirmed a large B-cell lymphoma restricted to the CNS, CD5-, IgM kappa + , of non-germinal center-like phenotype, BCL2 + , MYC + , with strong proliferation (> 90%), EBV negative. This evidence concerns the gene CD5 and B-cell non-Hodgkin lymphoma.