Kaposi's sarcoma is the most common neoplasm affecting AIDS patients, affecting almost 20% of patients with AIDS, who are not on Anti retroviral therapy (ART). KS is characterized by purple or bluish-red lesions, which are actually vascular channels, filled with blood and cancer cells. These lesions initially appear on the feet or ankles, thighs, arms, hands, face, lining of the mouth, nose and throat, and later spread on to the lungs and other vital organs. Aggressive forms of the disease are capable of spreading to the bones, whereas some other fatal forms spread through the lymph nodes to vital organs. Infection with Human Herpes Virus-8 (HHV-8) is the most important factor in the development of Kaposi's sarcoma. In fact, infection with HHV-8 increases the risk of developing KS by almost 12 times. Co-infection with HIV further, dramatically increases the risk of KS.
Studies indicate that Kaposi's sarcoma is a monoclonal neoplasm, in which multicentric tumors originate from a single clone of precursor cells. The presence of this disease in men more than women indicates a hormonal nature in its epidemiology. Various studies have revealed that HIV and HIV-encoded products interact with human cells to produce immune cytokines, the most prominent of them being IL-6.