IL6 and primary central nervous system lymphoma: Innovative CSF diagnostic biomarkers exists, such as IL-10 and CXCL13 concentrations, IL-10/IL-6 ratio, B-cell clonality studies and MYD88 mutation analysis, but they need to be validated in larger clinical studies and their use need to be better standardized, in order to improve the diagnosis and management of patient with PCNSL.