Case Report: Hemorrhagic Vasculitis in a Patient With Multiple Sclerosis Receiving Fingolimod.

Fingolimod is an effective therapy for relapsing-remitting multiple sclerosis (RRMS) but predisposes patients to opportunistic infections, including varicella-zoster virus (VZV). We report a case of a 27-year-old Iranian man with a history of MS, stable on fingolimod for two years, who presented with worsening paresthesia and headache. His condition acutely deteriorated, leading to a diagnosis of VZV-associated cerebral vasculitis, intracerebral hemorrhage, and myelitis, confirmed via cerebrospinal fluid PCR and angiography. This case underscores that patients on fingolimod can develop severe, atypical neurological complications from VZV reactivation, even in the absence of cutaneous signs. A high index of suspicion and prompt diagnostic workup are crucial for early antiviral and immunomodulatory treatment to improve outcomes.