An Adult Case of Herpes Simplex Virus-associated Granulomatous Encephalitis.

Brain granuloma occurs under certain conditions. Herpes simplex virus (HSV) causes granulomatous encephalitis in children; however, it has been rarely reported in adults. A 74-year-old man with a history of herpes simplex encephalitis suffered recurrent seizures. Brain magnetic resonance imaging revealed a mass lesion and resection was performed. A polymerase chain reaction using a brain biopsy specimen was positive for HSV DNA; thus, the patient was diagnosed with HSV-associated granulomatous encephalitis. After administering acyclovir, the patient showed improvement. HSV can cause granulomatous encephalitis in adults, and acyclovir can be used for its treatment.