A pathological and immunohistological case report of fatal infectious mononucleosis, Epstein-Barr virus infection, demonstrated by in situ and Southern blot hybridization.

We present an autopsy case of 20-month-old boy who had a fulminant course of infectious mononucleosis, with severe hepatic failure. Autopsy revealed marked infiltration of immunoblasts in the lymph nodes, liver, spleen, thymus and kidneys. We identified a large number of Epstein-Barr virus (EBV) genomes in the immunoblasts of the lymph nodes, liver and spleen by in situ hybridization. EBV genomes were also detected in the liver and spleen by Southern blot hybridization. Histology of the liver revealed diffuse feathery degeneration of the hepatocytes. However, EBV genomes were not detected in the hepatocytes by in situ hybridization and monoclonal antibody studies. Immunostaining of the autopsy liver specimen revealed a large number of suppressor/cytotoxic T cells (Leu2a positive) in the portal areas and of natural killer (NK) cells (Leu7 positive) in the portal areas and sinusoids of the liver. We therefore suggest that the hepatocellular damage was not caused by the viral replication in the hepatocytes but was mainly caused by the abnormal killer cell activity of the suppressor/cytotoxic T cells and NK cells.