Isolated neurosarcoidosis - MR findings and pathologic correlation.

Neurosarcoidosis is a diagnostic challenge, especially if systemic symptoms are absent. We present a 49-year-old woman with isolated neurosarcoidosis. The main symptom was loss of vision in the left eye. Brain MR imaging showed 6 high-signal white matter lesions frontotemporally on proton density and T2-weighted turbo spin-echo images. Coronal fat-saturated turbo FLAIR images of the orbits showed a swollen left optic nerve with increased signal intensity, which finding has not been previously published in sarcoid optic neuropathy. A control MR examination showed meningeal enhancement of the left optic nerve and leptomeningeal enhancing lesions around the brain stem. Spinal MR revealed leptomeningeal enhancement throughout the spinal cord and asymptomatic enhancing cauda equina lesions, mimicking subarachnoid tumour seeding, and an enhancing nerve root mass at Th12/L1. Biopsy of the latter lesion revealed non-caseating granulomas consistent with sarcoidosis.