Incidental discovery of herpes simplex virus encephalitis by post-mortem MRI

Abstract

We describe a case of a 61-year-old man who was found dead at home. He was not known for any illness and no symptoms were described before death. At autopsy, signs of pneumonia were detected. The macroscopically examination of the brain revealed no pathological findings. The microscopically evaluation of the brain showed small groups of inflammatory cells in the brainstem. The detailed analyze of MR images of the brain, showed an hypo-intensity on T1-weighted images and an hyper-intensity on T2-weighted images of the frontal and temporal lobes with damage of the cingulate cortex, the limbic lobe and the left insular cortex. These images raised the suspicion of an herpes simplex virus encephalitis. Neuropathological and immunohistochemical investigations, which thus were carried out, showed various infiltrates of CD3+ and CD8+ T-cells in the brainstem. Additionally to these infiltrations, we found CD68+ macrophages and activated microglia. Furthermore we could, immunohistochemically, show a HSV-1 and HSV-2 positivity of the hippocampi. With this case report we would like to show the difficulty to diagnose the herpes simplex encephalitis in postmortem and how easy a diagnosis can be missed, especially if the person doesn’t show any symptoms before death. In order to detect this kind of encephalitis several examinations must be performed; but for initiating these examinations the clinical history must be known and the suspicion of an encephalitis must be evocated. Moreover, this case underlines the importance of MRI for the correct evaluation of the brain and the value of interdisciplinary work for medico-legal cases.

Keywords

• Herpes simplex
• Encephalitis
• MRI
• Autopsy