A Case of Neurosyphilis Radiologically Mimicking Herpes Simplex Encephalitis

The neuroradiologic findings of neurosyphilis are variable. A 36-year-old man was admitted due to gradually progressing abnormal behavior and personality change. The brain MRI revealed bilateral mesiotemporal hyperintensity on FLAIR and T2 weighted MR images. Analysis of serum and CSF demonstrated the presence of antibodies to Treponema pallidum. The patient was treated with penicillin, and he had clinical improvements. Neurosyphilis can manifest with MR imaging abnormalities similar to those of herpes encephalitis.