Solitary Cavernous Sinus Neurosarcoidosis Mimicking Neurosyphilis
A 40-year-old man experienced the sudden onset of diplopia one month before admission. At that time, he was evaluated for his ophthalmoplegia in an outside hospital with brain magnetic resonance imaging (MRI), which demonstrated right sphenoid and left posterior ethmoid sinusitis. One month after the onset of diplopia, he still suffered from diplopia. He also developed a new onset of right facial pain and headache. The follow-up MRI revealed an enhancing mass lesion in the right cavernous sinus region. He was referred to our neurosurgical unit with the presumptive diagnosis of a cavernous sinus tumor.\nHe had a history of syphilis of unknown stage, which had been treated 20 years earlier. At admission, he was alert and fully oriented. He presented with diplopia, headache, right facial pain, and mild dysarthria. The neurological examination was notable for the complete palsy of abduction in his right eye, paresthesia in all divisions of the right trigeminal nerve and right facial palsy with mild dysarthria. There was no tinnitus, uvula deviation, or tongue deviation. In serum laboratory examination, his venereal disease research laboratory (VDRL) titer was 1 : 16. Treponema pallidum hemagglutination and fluorescent treponemal antibody absorption test were reactive. The serum angiotension-converting enzyme (ACE) level was 12.5 IU/L (normal range : 8.3-21.4 IU/L) and the HIV test was negative. The cerebrospinal fluid (CSF) examination revealed a normal opening pressure at lumbar puncture, 20 white blood cells (80% lymphocytes), no red blood cells, protein level of 41 mg%, and glucose level of 79 mg%. The CSF VDRL test was negative.\nBrain MRI demonstrated a lobulated mass predominantly involving the right cavernous sinus (). The mass extended toward the middle fossa laterally and to the sphenoid sinus anteriorly. This tumor also extended to the cerebellopontine angle posteriorly with a compression of the brain stem. The lesion appeared isointense on T1-weighted images and slightly hyperintense on the T2-weighted images. Moreover, the T2-weighted images revealed hyperintense signal changes in the pontine area. The mass showed strong enhancement after gadolinium administration. On the other hand, malignancy and inflammatory disorders were included in the differential diagnosis considering the rapid enlargement of mass and serological markers.\nA biopsy was performed via the transsphenoidal approach to make a precise diagnosis. The surgical approach was chosen based on the protrusion of pathology in the sphenoidal sinus and minimal invasive technique. A histopathological examination revealed a non-caseating granuloma with an asteroid body (). Special stains including periodic acid-Schiff, Ziehl-Neelsen stain for acid-fast bacilli and Gomori's methenamine silver stain for fungal organisms were negative. Chest and abdomen computed tomography were performed to exclude systemic sarcoidosis, but unremarkable.\nAfter administration of corticosteroid, the headache and facial paresthesia was improved but the diplopia has remained. The pathologic findings were consistent with a diagnosis of sarcoidosis, but the neurosyphilis could not be ruled out in the differential diagnosis due to the positive serologic result for syphilis. The patient received the treatment with intravenous penicillin G for 2 weeks and the steroid was tapered and discontinued. After 4 days of penicillin administration, the right side facial pain and paresthesia became aggravated. Therefore, we were confident in a diagnosis of neurosarcoidosis and resumed the steroid treatment. The facial pain disappeared again after steroid therapy. The steroid dose was tapered down and shifted to oral prednisolone in the third week. He was discharged with isolated right abducens nerve palsy. He received oral prednisolone at the outpatient department for one year and the abducens nerve palsy was improved. A follow-up MRI of the brain revealed resolution of the mass over the cavernous sinus region ().