Neurosyphilis with unilateral optic tract lesion causing homonymous hemianopia.

Introduction: Homonymous hemianopia is not a rare symptom. Many causative lesions and pathologies are known, although a unilateral optic tract lesion caused by syphilis is rare.
Case Report: A 56-year-old woman developed a congruous right homonymous hemianopia and bilateral tonic pupils with irregular shape. Brain T2-weighted and fluid attenuated inversion recovery magnetic resonance imaging (MRI) revealed a spindle-like high-intensity lesion in her left postchiasmal optic tract. The rim of this lesion enhanced with gadolinium without meningeal enhancement. Serum and cerebrospinal fluid venereal disease research laboratory tests were positive. Cerebrospinal fluid contained 71 white blood cells/microL (mononuclear cells = 97%) and 48 mg/dL of protein. The hemianopia disappeared after administration of benzylpenicillin.
Conclusions: Neurosyphilis should be added to the list of differential diagnoses for an isolated optic tract lesion.