Chronic Granulomatous Herpes Simplex Encephalitis: An Unusual Manifestation of an Enduring Viral Infection

Abstract Chronic granulomatous herpes simplex encephalitis (CGHSVE) is a rare viral encephalitis phenotype that occurs due to granulomatous inflammation in the brain, mounted in response to persisting herpes virus antigens. Our case is that of a young adolescent who presented with recurrent seizures with serial magnetic resonance imaging showing asymmetric lesions in bilateral temporal lobes with gyral enhancement, biopsy of which was suggestive of granulomatous vasculitis. Cerebrospinal fluid polymerase chain reaction (PCR) for herpes simplex virus (HSV) antigen was negative. PCR done on the brain tissue was positive for HSV DNA. The patient also had a good response to oral valacyclovir. CGHSVE should be considered as a differential diagnosis in subjects with imaging suggestive of progressive temporal lobe lesions with enhancement. Brain biopsy is confirmatory. Treatment response with oral antivirals is usually favorable.