Neurosyphilis may affect the optic nerves, resulting in acute vision loss, papilledema, and optic nerve atrophy. We present a patient whose symptomatology was initially suspicious for giant cell arteritis, but who was later found to have neurosyphilis.

A 59-year-old man with history of obstructive sleep apnea, hyperlipidemia, irritable bowel syndrome, and depression presented with a five-day history of painless monocular central vision loss in the left eye. He also endorsed a four-week history of malaise, diffuse arthralgias, and new stabbing left temporal headache. On physical examination, patient had bilateral papilledema, left central visual field cut with red-desaturation, as well as joint tenderness. Laboratory studies were notable for erythrocyte sedimentation rate of 68 (range 0-15) and C-reactive protein of 11.4 (range 0.1-3.0). Computed tomography and angiography of the brain were unrevealing. Magnetic resonance imaging revealed increased T2 signal in the left optic nerve without contrast enhancement. Cerebrospinal fluid testing revealed clear fluid with 6 white blood cells (81% lymphocytes), normal glucose and protein. Patient was started on pulse intravenous glucocorticoids followed by oral prednisone for suspected giant cell arteritis. Temporal artery biopsy was negative. After several days, venereal disease research laboratory testing (VDRL) in CSF resulted positive with titer of 1:1. Subsequent serum testing was notable for positive rapid plasma reagin (RPR) with titer 1:128, and fluorescent treponemal antibody test absorption test of 4+, confirming syphilis. Patient was subsequently treated with penicillin, with complete resolution in his visual symptoms.

Ocular syphilis is an important diagnosis to consider on the differential for giant cell arteritis, given that the divergent treatment pathways and given the potential morbidity associated with misdiagnosis.