Although herpes simplex encephalitis is not classically considered an opportunistic infection, reactivation of herpes simplex is being seen increasingly in patients with cancer or immunosuppression. The authors present a patient with malignant glioma and HSV-1 encephalitis whose PCR-proven encephalitis recurred after temozolomide (TMZ) chemoradiation despite acyclovir therapy, and summarize details of four other cases of HSV-1 encephalitis associated with TMZ. The similarity among these cases raises the likely need for longer treatment courses and/or oral suppressive therapy in patients at risk for herpes simplex infections who are receiving TMZ.
