CXCL13 and primary central nervous system lymphoma: In fact, several studies reported CXCL13 as a potential marker of inflammation in CSF and high levels of this molecule have been reported in CSF during MS (RRMS, PPMS, and CIS disease courses)26–28 and NMO conditions73, while very high CSF levels have been described in MS mimics, such as CNS lymphoma, neuroborreliosis (where CXCL13 is described as a specific biomarker) and viral miningitis74.