The vast majority of CNSL cases are CD23 negative (80% PCNSL, 100% relapsed CNSL) as well as CD138 negative (91.7% PCNSL, 60% relapsed CNSL), and cyclin D1 negative (88.5% PCNSL, 80% relapsed CNSL). This evidence concerns the gene CCND1 and primary central nervous system lymphoma.