 Some 48%-63% of PBL cases occur in individuals with HIV/AIDS; ~80% of these HIV/AIDS-afflicted individuals have EBV+ disease whereas only ~50% of PBL individuals that do not have HIV/AIDS are EBV-positive.Individuals who develop PBL following organ transplantation are EBV-positive in >85% of cases.Most post-transplant and HIV/AIDS patients have an extremely aggressive disease.