Herpes simplex encephalitis occurring after chemotherapy, surgery, and stereotactic radiotherapy for medulloblastoma

Reactivation of latent herpes simplex virus (HSV) in the trigeminal ganglio n most commonly gives rise to recurrent herpes labialis and rarely to herpe s simplex encephalitis. The mechanisms underlying reactivation of latent tr igeminal HSV are complex. Here we report the case history of a 25-year-old woman who developed a fatal, bilateral necrotizing destructive temporal lob e lesion following surgical removal of a cerebellar medulloblastoma and com bined radiotherapy and chemotherapy for recurrent tumor. Neuropathologic ex amination of the brain revealed minimal inflammatory changes, but immunohis tochemistry was positive for HSV protein, and HSV deoxyribonucleic acid (DN A) was recovered from formalin-fixed paraffin;embedded brain tissue. The te mporal proximity of the surgery, chemotherapy, and radiotherapy to the onse t of disease suggests that these factors may have acted as triggers that pr ecipitated conversion of latent HSV to overt HSV.