I wondered the same thing... I collected some thoughts but haven't reached a clear conclusion on that. I tend towards common for unrelated reasons. Kaposi's Sa

I wondered the same thing... I collected some thoughts but haven't reached a clear conclusion on that. I tend towards common for unrelated reasons. Kaposi's Sarcoma (KS) is caused by a herpes virus: KSHV, https://en.wikipedia.org/wiki/Kaposi_sarcoma-associated_herpesvirus https://en.wikipedia.org/wiki/Kaposi_sarcoma-associated_herp... We see KS in HIV patients because they are often concomitant infections and because KS is opportunistic, attacking immune-suppressed people. But, this doesn't mean that KS necessarily goes hand-in-hand with HIV infection. Particular forms of KS affect younger people: https://en.wikipedia.org/wiki/African_cutaneous_Kaposi_sarcoma https://en.wikipedia.org/wiki/African_cutaneous_Kaposi_sarco... https://en.wikipedia.org/wiki/African_lymphadenopathic_Kaposi_sarcoma https://en.wikipedia.org/wiki/African_lymphadenopathic_Kapos... KS may have been 9% of all cancers in equatorial Africa just because of a very high KSHV prevalence and because lower life expectancy = fewer age-related cancers. There was a similar rate recogised since the 1950s http://www.nejm.org/doi/full/10.1056/NEJM200004063421407 http://www.nejm.org/doi/full/10.1056/NEJM200004063421407 This article also notes that KS now accounts for 50% of tumours in some countries, with and without HIV infection. An NHS article which admits that, even today, they're not exactly sure how many incidents of KS are HIV-related http://www.nhs.uk/Conditions/Kaposis-sarcoma/Pages/Introduction.aspx http://www.nhs.uk/Conditions/Kaposis-sarcoma/Pages/Introduct...