Viral oncogenesis: Epstein-Barr virus.

The Epstein-Barr virus (EBV) is a common herpesvirus that has been linked to several human neoplasms. It has been found in over 90% of cases of Burkitt's lymphoma in endemic regions, although only 15% of cases in nonendemic regions show evidence of infection. The virus has been found in malignant lymphomas in immunocompromised states, including the acquired immunodeficiency syndrome, iatrogenic immunosuppression, such as in posttransplantation patients, and congenital immunodeficiencies. Recently, EBV genomes have been found in approximately 25% of cases of Hodgkin's disease, where it has been found in the Reed-Sternberg cells. Epstein-Barr virus genomes are found in over 90% of cases of undifferentiated nasopharyngeal carcinoma. In addition, EBV has been identified in undifferentiated carcinomas in other sites in Asians, such as carcinomas of the parotid in Chinese individuals and Eskimos.