Abstract We present a case of sarcoidosis in a 14-year-old girl who presented with a short history of visual disturbance. Computed tomography and magnetic resonance imaging (MRI) demonstrated enlargement of the optic chiasm and prechiasmic optic nerves. Post-contrast MRI showed marginal enhancement of the affected areas of the optic pathways. A diagnosis of optic nerve glioma and arachnoid gliomatosis was made; surgical confirmation was not sought due to the risk to vision associated with biopsy. A rapid clinical deterioration led to repeat MRI which demonstrated extensive enhancing soft tissue throughout the basal cisterns with extension into the brain. Biopsy confirmed a diagnosis of sarcoidosis.