Tumefactive multiple sclerosis which initially presented with brainstem encephalitis with a long-term follow-up.

Tumefactive demyelinating lesions (TDLs) are rare in multiple sclerosis (MS). We herein report a case of tumefactive MS which initially presented with brainstem encephalitis with a long-term follow-up. The patient had experienced relapse mostly in the brainstem in the first twenty years, and then in the periventricular white matter afterwards. The patient responded well to steroid treatment recovered without sequalae. However, immunodeficiency due to the long-term use of oral prednisolone made aggressive therapy during the relapse impossible, so recovery after steroid therapy is incomplete. Our case is different from classical MS in clinical course and response to treatment. Our report offers rare information on long-term outcome of tumefactive MS.