Etiology of endemic Kaposi's sarcoma.

The exact etiology of Kaposi's sarcoma (KS) remains unknown. Certain observed features suggest a possible viral etiology, including: (a) the spontaneous regression of indolent forms; (b) the frequent occurrence of second primary malignancies; (c) the multifocal nature of KS. Electron microscopic studies have revealed herpesvirus-type particles which morphologically resemble cytomegalovirus (CMV). Sera from KS patients in Europe and America have higher anti-CMV antibodies than controls, in contrast to African patients, whose CMV antibody titres are not significantly different from those of controls. This difference may be related to the high background of CMV antibody in the general African population. Nucleic acid hybridization studies have revealed CMV DNA in some African KS tissue. The possible role of human T-cell leukaemia/lymphoma virus (HTLV) in the causation of KS is discussed in the light of recent evidence of its association with acquired immunodeficiency syndrome (AIDS). Similarly, the possible predisposing role of HLA-DR5 in patients with AIDS and KS is considered.