Sight-threatening optic neuropathy is associated with paranasal lymphoma.

Malignant lymphoma around the orbit is very rare. We present a rare case of optic neuropathy caused by lymphoma. A 61-year-old Japanese woman was referred to our hospital for evaluation of idiopathic optic neuropathy affecting her right eye. The patient was treated with steroid pulse therapy (methyl-predonisolone 1 g daily for 3 days) with a presumed diagnosis of idiopathic optic neuritis. After she had been switched to oral steroid therapy, endoscopic sinus surgery had been performed, which revealed diffuse large B cell lymphoma of the ethmoidal sinus. Although R-CHOP therapy was immediately started, prolonged optic nerve compression resulted in irreversible blindness. Accordingly, patients with suspected idiopathic optic neuritis should be carefully assessed when they show a poor response, and imaging of the orbits and brain should always be done for initial diagnosis because they may have compression by a tumor.