Composition of the BBB and therapeutic strategy for PCNSL. The BBB is a physical barrier formed by endothelial cells connected by tight junctions, the basal lamina, pericytes and astrocyte end-foot processes to protect the brain from attack by circulating microorganisms, chemicals and metabolites. However, it results in relatively low delivery of therapeutic agents to brain tissue from the blood. PCNSL is a type of lymphoma involving only the CNS at the onset, and most cases are pathologically diagnosed as DLBCL. Multi-signaling pathways relating to B-cell development and activation are involved. In addition to conventionally applying high-dose small-molecule chemotherapy during induction and ASCT or WBRT during consolidation, more specific targets in B cells and the BCR signaling pathway, immune microenvironment regulation and BBB permeabilization can be exploited for precision therapy for this disease entity.