Fulminant multifocal relapse in a fingolimod-treated multiple sclerosis patient.

Background: Fingolimod is the first approved oral disease-modifying treatment for relapsing-remitting multiple sclerosis. Fingolimod targets lymphocytes, exerting a modulator effect on cell-surface sphingosine-1-phosphate receptors and thus blocking lymphocytes egression from secondary lymphoid organs. Recent reports describe fingolimod cessation being followed by severe or pseudo-tumoral relapse, but it usually does not happen on continuous long-term treatment.

Case Presentation: Here we present the case of a patient on continuous long-term fingolimod treatment who presented with fulminant atypical multifocal relapse involving over 30 new and active lesions.

Conclusion: This case is unique since this fulminant multifocal relapse occurred in a patient with grade 3 lymphopenia and irreproachable adherence. This observation should be known as a possible side effect of fingolimod treatment.