Causes
Researchers don't know what causes Kaposi's sarcoma. There is a known increase in the condition among people who have a depressed immune system, such as those with AIDS, or those taking immunosuppressant therapy after receiving an organ transplant. The most likely cause of this condition is the combination of immune depression, as occurs with HIV infection, and exposure to the human herpesvirus 8 (HHV 8), a sexually transmitted infection. While the condition is most prevalent among sexually active homosexual and bisexual males with HIV, the improvement in the medical treatment of HIV appears to have reduced the incidence of this condition. The incidence of the condition in heterosexual people with HIV is far lower.