A differential diagnosis between neurosarcoidosis and neurosyphilis is particularly problematic in patients with a positive serologic result for syphilis. We report here a patient with a solitary cavernous sinus sarcoidosis who had a history of syphilis and showed rapidly progressing cavernous sinus syndrome. A transsphenoidal biopsy was performed and a histopathologic examination revealed a non-caseating granuloma with an asteroid body. His facial pain disappeared after steroid therapy. He received oral prednisolone for one year. A follow-up magnetic resonance imaging of the brain revealed resolution of the mass over the cavernous sinus. Particularly in patients with a history of syphilis, neurosyphilis should be included in a differential diagnosis of neurosarcoidosis.