Severe tumefactive rebound of multiple sclerosis following fingolimod cessation

Fingolimod is an oral sphingosine-1-phosphate receptor modulator approved for the treatment of active relapsing-remitting multiple sclerosis (RRMS). Recent reports have highlighted the possible risk of rebound disease activity after withdrawal of fingolimod. We describe a case of a patient who developed severe tumefactive lesions on discontinuing fingolimod treatment. A 32-year-old woman with RRMS escalated treatment from interferon β to fingolimod due to ongoing relapses. She developed side effects on fingolimod including persistent lymphopenia (<0.3). The fingolimod dose was reduced to alternate days. The patient noticed cognitive decline with progressive memory loss. JC-virus serology was previously positive, with a titre of 2.41. Cerebrospinal (CSF) studies and MRI were performed to exclude progressive multifocal leukoencephalopathy (PML). …