The ectopic lymphoid follicles are composed of B-cells, T follicular helper cells and follicular dendritic cells. Rituximab is a monoclonal antibody against CD-20 (a B-cell marker) that is FDA approved for the treatment of various lymphomas. Intrathecal (IT) rituximab administration has been used in central nervous system (CNS) lymphoma to achieve greater cerebrospinal fluid (CSF) concentrations of rituximab. In MS, IT administration of rituximab could lead to higher CSF rituximab levels resulting in the disruption of meningeal ectopic lymphoid follicles, ultimately reducing cortical lesions and possibly disease progression.