BCR and primary central nervous system lymphoma: Frequent mutations in the B-cell receptor (BCR) and Toll-like receptor 9 (TLR9) pathways (9, 10) with transcriptional upregulation of NF-kB, overrepresentation of the autoimmunity-linked immunoglobulin gene VH4-34 (5, 11) and persistent expression of functional BCRs despite ongoing somatic hypermutation (7), all indicate an important role of antigenic BCR stimulation in the pathogenesis of PCNSL (12).