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 AIDS 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.
As AIDS became more widespread, KS became the most common cancer found in people with acquired immunodeficiency syndrome (AIDS), occurring as a complication of late AIDS. In people with AIDS, the tumour grows and spreads more quickly than in elderly men without AIDS. As HIV infection has now become better controlled, KS is once again becoming an infrequent condition.