Abstract
We report the case of a 91-year-old man with varicella zoster virus (VZV) meningoencephalitis who presented with acute progressive delirium. Brain MRI revealed multiple small vessel lesions, and cerebrospinal fluid testing came back positive for VZV DNA by polymerase chain reaction. We assume that VZV had reactivated since he was elderly and had lung cancer. The fact that there were no skin eruptions in the early stage made the diagnosis difficult. If a patient without skin rashes presents with acute progressive cognition, VZV should also be listed in the differential diagnosis.