Hepatitis C virus (HCV) reactivation during fingolimod treatment for relapsing and remitting multiple sclerosis.

We here report a case involving a 38-year-old female with relapsing and remitting multiple sclerosis who developed reactivation of hepatitis C virus (HCV) during administration of fingolimod for 16 months. She had been previously treated for chronic hepatitis C with pegylated interferon and ribavirin, and kept an undetectable HCV-RNA state for more than 4 years before fingolimod starting. Although the increased risk for viral reactivation, for example of herpes zoster virus and varicella-zoster virus, during fingolimod treatment is known, this is, to our knowledge, the first case report of HCV reappearance.