A rare suspected case of chronic nodular granulomatous herpes simplex encephalitis in an adult.

Herpes simplex encephalitis is the most common sporadic viral encephalitis in the western world, HSV-1 (herpes simplex virus) being the mostly commonly implicated serotype. The disease is usually monophasic, although patients may relapse weeks, months or years after initial infection. This chronic granulomatous inflammatory process is almost exclusively described in children and rarely forms discrete enhancing parenchymal nodules. We present the clinical and radiological features of an unusual case of chronic nodular granulomatous herpes encephalitis with enhancing "mass-like" nodules in an adult. To the author's knowledge, this is the first reported case of macroscopic "mass-like" nodular granuloma formation in an adult.