Lethal multiple sclerosis relapse after natalizumab withdrawal

Natalizumab dramatically reduces relapses in patients with active multiple sclerosis (MS), but it may induce progressive multifocal leukoencephalopathy (PML).1 A rebound of MS or an immune reconstitution inflammatory syndrome (IRIS) were described after natalizumab withdrawal, even in the absence of PML.2,3 Very few data concerning the potential severity and the neuropathology of this event are available. We report the case of a 50-year-old patient with MS who developed a fulminating relapse 3 months after stopping natalizumab, leading to death despite intensive care and immunosuppressive therapy. Radiologic and neuropathologic findings provide interesting data regarding the nature of the rebound. Acknowledgment: The authors thank Drs. P. Morgan and S. Piddlesden, University of Cardiff, UK, for providing the C9neo antibody.