Isolated neurosarcoidosis mimicking multiple sclerosis.

Patients with isolated neurosarcoidosis (NS) can present with neurological symptoms that mimic other neurologic conditions, such as multiple sclerosis (MS). In this article, we present a case of 25-year-old man with a transverse myelitis. Magnetic resonance imaging (MRI) of the brain and spine showed several, periventricular, infratentorial, and spinal cord white matter lesions. He was diagnosed with MS and was started on fingolimod, which did not result in any improvement. Follow-up brain and spine MRI showed a longitudinally extensive lesion with leptomeningeal enhancement. Leptomeningeal and cerebellar biopsy showed non-necrotizing granulomas consistent with neurosarcoidosis. Fingolimod was discontinued. The patient was treated with oral prednisone and infliximab, which ceased the progression of the disease and allowed for slow improvement. Incorrectly diagnosing NS with MS or vice-versa, not only deprives patients of beneficial therapy, but also potentially exposes them to therapies that may be harmful.