Background: The evidence of an infectious agent other than human immunodeficiency virus (HIV) acting as a possible etiologic cause of Kaposi's sarcoma (KS) has received considerable attention in the last years. Recently, DNA sequences from a new herpesvirus (HHV-8) have been observed in several cases of KS. The discovery suggests that this virus may play a role in the pathogenesis of KS. To evaluate these results, we determined the frequency of HHV-8 DNA sequences in 78 specimens of KS according to different epidemiologic origins (sporadic KS: 6, immunosuppressive drug-associated: 11, and AIDS-associated: 61), clinical forms (cutaneous: 69, mucocutaneous: 4 and visceral; 5) and histologic variants (early-patch: 40, late-plaque or nodular: 38).
Methods: We used the hot start polymerase chain reaction amplification method with KS330 primers specific for HHV-8 DNA. Tumoral or nontumoral skins and visceral specimens free of KS, originating from patients with KS positive for HHV-8 DNA sequences or from immunosuppressed patients without KS, served as controls. Normal skin from healthy HIV seronegative patients was also included.
Results: HHV-8 DNA sequences were found in 3 of the 6 sporadic KS (50%), in 5 of the 11 immunosuppressive drug-associated KS (45%), in 41 of the 61 AIDS-associated KS (67%), in 32 of the 69 cutaneous KS (46%), in 3 of the 4 mucocutaneous KS (75%) in 2 of the 5 systemic KS (40%), in 23 of the 40 early or patchstage KS (58%), in 30 of the 38 late plaque or nodular stages KS (79%). These sequences were also demonstrated in one sample of skin with scabies and in a glomerulonephritis lesion from two immunosuppressed patients with KS who were also positive for herpesvirus-like in their KS lesions. None of the other skin or visceral specimens, originating from healthy, AIDS, or transplanted patients without KS, were positive.
Conclusions: Our results reinforce the hypothesis that HHV-8 is incriminated in different epidemiologic, clinical and histologic stages of KS and could contribute to the pathogenesis of this tumor. However, the presence of HHV-8 DNA sequences in skin and visceral samples free of KS from KS indicates that the virus is not restricted to the tumor tissue, and thus is able to disseminate in many organs of the target individual. Absence of the virus from healthy, AIDS, or transplanted patients without KS suggests that the viral Sequences either do not spread easily or do not easily maintain themselves in the human population.