Anorectal melanomas do not harbour the Kaposi sarcoma-associated human herpesvirus type 8 DNA

Anorectal melanomas are similar to cutaneous melanomas with regard to the mode of spread and to the immunophenotype. When compared with patients with cutaneous melanoma, those suffering from anorectal melanoma have a much worse outcome. The etiology of anorectal melanomas is as yet completely unknown. For anatomical reasons, ultra-violet (UV-B) radiation can not cause anorectal melanomas as in cutaneous tumours, that are associated with exposure of the skin to UV-B radiation. As the cytokine interleukin-6 (IL-6) is known to stimulate melanoma tumour cell proliferation and a functional homologue of human IL-6 has been identified recently in the HHV-8 genome, this tumorigenic virus might be involved in the pathogenesis of anorectal melanomas. Twelve formalin fixed and paraffin embedded primary anorectal melanomas from seven female and five male patients with a mean age at diagnosis of 71 years (range 38-88 years) were investigated for the presence of HHV-8 DNA. Using a specific and highly sensitive polymerase chain reaction protocol, this tumorigenic gamma-herpesvirus was not detectable in any tumour. This data indicates that HHV-8 is not involved in the development of anorectal melanomas.