A Neurosyphilis Case Mimicking Herpes Simplex Virus Encephalitis in an African American Male.

Neurosyphilis is one form of a multisystemic sexually transmitted disease caused by Treponema pallidum. Although typical presentations of neurosyphilis have become less common in the post-antibiotic era, a rising trend of atypical presentations can mimic other diagnoses like herpes simplex and autoimmune encephalitis. In this case, we diagnosed neurosyphilis in a patient with clinical and radiological features similar to herpes simplex encephalitis. We emphasize the need for a diagnostic approach combining imaging namely MRI, lumbar puncture, and use of treponemal and non-treponemal tests so that neurosyphilis cases with atypical neuroimaging findings are not overlooked.