CXCL13 and primary central nervous system lymphoma: Notably, such a scenario perfectly complies with the current knowledge about intrathecal sources of CXCL13, which are heterogeneous and include inflammatory microglia in actively demyelinating CNS lesions, FDC, and CXCL13-producing Tfh and Tfh-like cells in meningeal tertiary lymphoid structures (TLS), perivascular follicular stromal cells in CNS lymphoma, and intrathecal macrophages in LNB [36,37,38,40,144].