Sarcoidosis presenting as optic neuritis with vision loss

Neurosarcoidosis is a rare complication of sarcoidosis and unusually presents as optic neuritis. We present the case of a 51‐year‐old man who complained of right vision loss. Brain magnetic resonance imaging showed asymmetrical enlargement of the right optic nerve. Chest computed tomography detected mediastinal and hilar lymphadenopathy. There were cutaneous nodules on the back. Biopsy of the mediastinal lymph node by endobronchial ultrasound‐guided transbronchial needle aspiration and the skin showed noncaseating granulomas consistent with sarcoidosis. Serum angiotensin‐converting enzyme level was elevated (34.2 IU/L) (normal: 8.3–21.4 IU/L). Based on these findings, he was diagnosed as neurosarcoidosis with optic neuritis. He was started on 1000‐mg/day methylprednisolone intravenously for 3 days, followed by oral 50‐mg/day prednisolone, which was gradually tapered for 8 weeks. Thereafter, the skin nodules and lymphadenopathy decreased and the right vision partially improved. Based on this rare case, sarcoidosis should be considered as a differential diagnosis in cases of optic neuritis.