Kaposi's sarcoma (KS) is a cancer caused by infection with human herpesvirus 8 (HHV8). It causes purple, brown, or bluish-red tumours that look like sores on the skin. It may also affect the internal organs and the mucous membranes lining the mouth, nose, and anus.
Before HIV infection became widespread, Kaposi's sarcoma was uncommon and usually only found in elderly men, usually of Italian, Jewish, or African descent. It was also infrequently found in people who had received organ transplants and were taking immunotherapy to avoid organ rejection.
With the development of the HIV/AIDS epidemic KS became the most common cancer found in people with acquired immunodeficiency syndrome (AIDS), occurring as a complication of advanced HIV disease.
In people with HIV, the tumour grows and spreads more quickly than in elderly men without HIV. As HIV infection has now become better controlled, KS is once again becoming an infrequent condition.