Severe fingolimod rebound syndrome after switching to cladribine treatment.

We present the clinical and imaging characteristics of a patient whom presented with rebound syndrome after switching from fingolimod to cladribine treatment due to hematologic toxicity. Previous imaging studies had shown a non-aggressive phenotype of the disease, however multiple active tumefactive lesions became evident after beginning treatment with cladribine. The patient responded well to plasmapheresis.