Sudden child death with acute encephalitis due to human herpesvirus 7: A case report and review of the literature

Human herpesvirus 7 (HHV-7) infection is known to cause severe symptoms and conditions in immunocompromised children. This case report presents the forensic autopsy case of a 7-year-old immunocompetent boy with acute encephalitis due to HHV-7, along with a review of the literature for similar cases. On macropathological examination, the brain was congested and edematous with mild cerebral herniation. Histopathological examination of the brain revealed edematous nerve cells with acidophilic changes. Intracellular inclusion bodies and neuronophagia were observed particularly in the frontal and temporal lobes. Infiltration of lymphocytes was observed in the arachnoid matter and around small blood vessels in the cerebral basal ganglia (perivascular lymphocytic cuffing). Glial nodules were observed in the parietal lobe, basal ganglia, and the medulla oblongata. In addition, necrosis and gliosis were observed in part of the cerebral basal ganglia. The polymerase chain reaction (PCR) test of cerebrospinal fluid (CSF) was positive for HHV-7. Postmortem blood biochemical examination for antibodies was positive for immunoglobulin (Ig) G and negative for IgM to HHV-7. The cause of death was diagnosed as acute encephalitis due to HHV-7. In general, encephalitis due to HHV-7 develops in immunocompromised patients undergoing transplantation or chemotherapy. However, our fatal case of HHV-7 encephalitis occurred in an immunocompetent child, which is rare. Forensic scientists should be careful when diagnosing HHV-7 encephalitis, since there are no characteristic findings, except for brain edema, on macropathological examination.