A 42-year-old homosexual man came to the emergency department because of fever, headache, and hearing loss. Fever and headache had been fluctuating for 2.5 months before and hearing loss was progressive for 1 week. He experienced a generalized maculopapular rash 2 months before admission. On clinical examination, the patient was subfebrile (temperature, 37.7°C) and had bilateral sensorineural hearing loss and a stiff neck. Brain imaging demonstrated right frontal edema surrounding a small contrast-enhancing lesion (Figure) and a smaller focus at the convexity of the anterior left frontal cortex. Blood analysis showed a lymphocyte count of547/μL (normal range, 1500-3500/ μL) with a CD4 cell count of 128/μL (normal range, 455-1885/μL). Serology for human immunodeficiency virus (HIV) 1 was positive. Lumbar puncture showed a white blood cell count of 1010/μL of which 64% were polymorphonuclear leukocytes; hypoglycorrhachia of 16 mg/dL (blood glucose level, 5.27 mmol/L [95 mg/dL]); a protein level of 0.17 g/dL; and a lactate level of 50 mg/dL. The IgG index was 1.27, and there were 16 oligoclonal bands. Bacterial, mycobacterial, and fungal cultures were negative for organisms, as were polymerase chain reaction studies for herpes simplex, cytomegalovirus, toxoplasma, JC virus, and mycobacteria. No cryptococcal antigen was detected. Antibodies against Borrelia burgdorferi were negative in serum and cerebrospinal fluid (CSF). Antitreponemal antibodies were positive in serum and CSF. The VDRL test result was 1/16 in serum and 1/8 in CSF, which is considered diagnostic for neurosyphilis.1 After 3 weeks of intravenous treatment with penicillin G and ampicillin, symptoms and imaging findings rapidly resolved.