Kaposi's sarcoma (KS) is a form of cancer. It can cause lesions on the skin, mucus membranes, or internal organs such as the gastrointestinal tract and lungs.

KS can be classified according to the group of people that it affects:

  • Classic—usually affects men of Mediterranean descent
  • Endemic—usually affects people living in equatorial Africa
  • Transplant-related (acquired)—affects people who have received an organ transplant and have a suppressed immune system
  • AIDS-related (epidemic)—affects people with HIV infection

Cancer occurs when cells in the body divide without control or order. If cells keep dividing, a mass of tissue forms. This mass is called a growth or tumor. Malignant tumors can invade and destroy nearby tissue. Some types of cancer will eventually spread to other parts of the body.

KS is caused by an infection with a specific virus. The virus is called human herpes virus 8 or Kaposi sarcoma herpesvirus (KSHV). Most people infected with the virus will not get KS. KS most often develops in people who have the virus and also have a weakened immune system.