Kaposi sarcoma (KS) is a soft-tissue tumor that arises in people infected with the human herpes virus-8 (HHV-8). It begins in the cells that form blood or lymph vessels and first appears as distinctive deep purple or reddish blue lesions on the skin; in the lining of the mouth, nose, or throat; or in the gastrointestinal tract.
Named after the Hungarian dermatologist who first identified the disease in the 1800s, KS was uncommon in the US before the spread of HIV/AIDS in the 1980s. Fewer than one in ten Americans have the HHV-8 virus, which rarely causes symptoms or illness.
People who are infected with HHV-8 may develop KS if their immune system is too weak to suppress the virus due to HIV infection, the use of organ transplant drugs, advanced age, or other factors.
Thanks to advances in AIDS treatment, the number of people with AIDS-related KS in the US has declined dramatically since the mid-1990s. But it is still the most common cancer in Americans with HIV/AIDS and is also one of the most common cancers in sub-Saharan Africa.
Types of Kaposi Sarcoma
The HIV/AIDS-associated form of KS is considered an “AIDS-defining” illness that marks the transition from HIV infection to AIDS. It is usually more aggressive than other types of KS, spreading more quickly and more widely throughout the body.
Other types of KS include:
- Classic KS, which occurs primarily in older people of Mediterranean, Eastern European, and Middle Eastern descent whose immune systems are weakened as a result of advanced age. People with this type of KS typically have one or more lesions on the legs, ankles, or soles of the feet.
- African KS, also known as endemic KS, which usually occurs in children and adults under age 40 who live near the equator in Africa.
- Immunosuppressive treatment–related KS, also called iatrogenic KS, which occurs in HHV-8-infected people who take immune-suppressing drugs to prevent the rejection of a transplanted organ. An estimated one in 200 people with a transplanted organ develop this type of KS within a year and a half of the operation.
- Nonepidemic Gay-Related KS is a rare disease that occurs in gay men who are HIV-negative. This type of KS progresses slowly. Lesions often appear on the extremities and genitals.
KS causes flat or slightly raised lesions or nodules (bumps) on the skin or mucous membranes in areas such as the lining of the mouth, nose, and throat. The lesions, which are composed of cancer cells mixed with blood cells, usually first appear on the nose or another part of the face, the hard palate (the hard, bony part of the roof of the mouth), or on the legs, feet, or other extremities.
In light-skinned people, KS lesions appear deep purple or bluish red. The lesions are brown or black in people with dark skin. KS patches and nodules are not itchy, but they may be painful if located in sensitive areas. Lesions on the legs or in the groin area may cause lymphedema (fluid-filled swelling) in the legs and feet.
KS lesions that have spread to the lungs can cause coughing, sometimes with blood, as well as shortness of breath or wheezing. Lesions in the digestive tract may lead to abdominal pain, diarrhea, or bleeding from the rectum.