HHV-8 infection in the transplantation setting: a concern only for solid organ transplant patients?

Early epidemiologic studies have shown an increased risk of Kaposi sarcoma (KS) in recipients of solid organ transplants, while KS is exceptional in the setting of autologous and allogeneic bone marrow (BM) and peripheral blood stem cell (PBSC) transplant patients. The recent discovery of human herpesvirus 8 (HHV-8) as the necessary etiologic agent of KS has stimulated studies to assess whether KS is the result of HHV-8 transmission from the donor or of reactivation of a pre-existing HHV-8 infection in the recipient host. An association of HHV-8 infection with lymphoid neoplasias has also been observed, identifying this herpesvirus as a possible causal agent of some Epstein-Barr virus negative post-transplant lymphoproliferative diseases. The recent description of non-neoplastic complications associated with HHV-8 reactivation after autologous PBSC transplantation, has raised concerns about the spectrum of diseases potentially associated with this herpesvirus, even in the setting of BM and or PBSC transplantation. The issue of HHV-8 transmission with the grafts, the problems inherent with the diagnosis and monitoring of active viral infection, the need for prevention and treatment of the clinical consequences of HHV-8 primary infection and reactivation cannot be underestimated, at least in areas endemic for HHV-8 infection.