Progressive Multifocal Leukoencephalopathy and Immune Reconstitution Inflammatory Syndrome after Discontinuation of Fingolimod Piñar Morales, Raquel Carrasco Garcia, María Gutiérrez Rojas, Luis Barrero Hernández, Francisco Javier Fingolimod Immune reconstitution inflammatory syndrome Magnetic resonance imaging Multiple sclerosis Progressive multifocal leukoencephalopathy R.P.M. and F.J.B.H. have contributed to the conception and design of the work. R.P.M. and M.C.G. have contributed to the acquisition, analysis, and interpretation of data for the work. L.G.R. and F.J.B.H. have contributed to drafting the work and revising it critically. All the authors have approved the version to be published. Progressive multifocal leukoencephalopathy (PML) is a rare complication of immunosuppressive treatment in MS patients. Immune reconstitution inflammatory syndrome (IRIS) appears after the withdrawal of certain drugs such as natalizumab (NTZ) or fingolimod. The development of PML-IRIS after NTZ treatment has been described, and its diagnosis is made by clinical and radiological criteria and the determination of the John Cunningham virus in CSF. We present a clinical case of a patient with MS who, after the withdrawal of fingolimod, developed PML-IRIS despite sustained lymphopenia. This is important for pharmacovigilance purposes, not only for NTZ but also for alternative drugs used in MS treatment. 2022-03-02T12:14:48Z 2022-03-02T12:14:48Z 2022-02-07 journal article Morales, R. P., Garcia, M. C., Gutierrez-Rojas, L., & Hernández, F. J. B. (2022). Progressive Multifocal Leukoencephalopathy and Immune Reconstitution Inflammatory Syndrome after Discontinuation of Fingolimod. Case Reports in Neurology, 14, 38-43. [https://doi.org/10.1159/000521944] http://hdl.handle.net/10481/73069 10.1159/000521944 eng http://creativecommons.org/licenses/by-nc/3.0/es/ open access Atribución-NoComercial 3.0 España S. Karger AG