Kaposi sarcoma is a type of cancer that forms in the lining of blood vessels and lymph vessels. The cancer forms growths of cells, called lesions, on the skin. The lesions often form on the face, arms and legs. The lesions may look pink, red, purple or brown.

Lesions also can appear on the genitals or in the mouth. In severe Kaposi sarcoma, lesions can be in the digestive tract and lungs.

The cause of Kaposi sarcoma is infection with the virus human herpes virus 8, also called HHV-8. In healthy people, this infection usually causes no symptoms because the immune system keeps it under control. In someone with a weakened immune system, however, HHV-8 can lead to Kaposi sarcoma.

There are four types of Kaposi sarcoma:

• AIDS-related or epidemic Kaposi sarcoma. This type happens in people infected with human immunodeficiency virus, also called HIV. HIV is the virus that causes AIDS.
• Transplant-associated or iatrogenic Kaposi sarcoma. This type happens in people who take medicine to control the immune system after an organ transplant.
• Classic Kaposi sarcoma. This type occurs in older men of Eastern European, Mediterranean and Middle Eastern descent. It usually grows slowly and can cause swelling in areas such as the legs.
• Endemic Kaposi sarcoma. This type affects young people in Africa. It can grow slowly on the skin or quickly inside the body.

Taking a piece of skin for testing

A health care professional may recommend removing a small piece of a skin lesion for testing. This procedure is called a skin biopsy. The sample is sent to a lab for testing. Lab tests can look for signs of cancer.

A skin biopsy can confirm Kaposi sarcoma.

Testing for Kaposi sarcoma inside the body

Other tests might be needed to look for Kaposi sarcoma in the lungs or the digestive tract.

Test to find Kaposi sarcoma in the digestive tract might include:

• Fecal occult blood test. This test detects hidden blood in stool. If it shows hidden blood, other tests might be needed to find the source. Other tests include an endoscopy or colonoscopy. These tests are used to see if Kaposi sarcoma is causing the bleeding.
• Endoscopy. In this test, a thin tube, called an endoscope, is passed through the mouth. It allows a health care professional to look at the esophagus, stomach and first part of the small intestine.
• Colonoscopy. In this test, a thin tube called a colonoscope goes through the rectum and into the colon. It allows a health professional to look at the walls of these organs.

Tests to find Kaposi sarcoma in the lungs might include:

• Chest X-ray. A chest X-ray might show something unusual in the lungs. If so, a CT scan of the chest or a bronchoscopy might be used to see to see if the unusual finding is Kaposi sarcoma.
• CT scan. This imaging test uses X-rays to make detailed images of the lungs.
• Bronchoscopy. In this test, a thin tube called a bronchoscope passes through the nose or mouth into the lungs. This allows for viewing the lining of the lungs and taking samples of lung tissue.

There's no cure for Kaposi sarcoma. But there are many treatment options that can help control it. Some people may not need treatment right away. Instead, the condition might be monitored to make sure it's not getting worse. Treatment depends on:

• The type of Kaposi sarcoma.
• Number of lesions and where they are.
• Effects of the lesions, such as causing pain or getting in the way of eating or breathing.
• Your overall health.

Treatment for AIDS-related Kaposi sarcoma

Thanks to better antiviral medicines to treat AIDS and ways to prevent it, Kaposi sarcoma has become less common and less severe in people with AIDS. Taking antiviral medicines can lower the amount of the virus that causes HIV/ AIDS and make the immune system stronger. This might be the only treatment needed for Kaposi sarcoma.

Treatment for transplant-related Kaposi sarcoma

Some people with transplant-related Kaposi sarcoma may be able to stop taking the medicines that are controlling the immune system or switch to another medicine.

Treatment for small skin lesions

These might include:

• Minor surgery, also called excision.
• Burning, called electrodessication, or freezing, called cryotherapy.
• Low-dose radiation, which is also helpful for lesions in the mouth.
• Laser therapy.
• An injection of the chemotherapy drug vinblastine into lesions.
• Applying a vitamin A-like medicine called a retinoid to the skin.

Lesions treated in any of these ways are likely to return within a couple of years. When this happens, treatment often can be repeated.

Treatment if there are many skin lesions

If the Kaposi sarcoma causes many skin lesions, other treatments might be needed, such as:

• Radiation therapy. Radiation therapy uses powerful energy beams to kill cancer cells. This is a treatment option if there are many skin lesions, but not enough to need chemotherapy.
• Chemotherapy. Chemotherapy uses strong medicines to kill cancer cells. Chemotherapy might an option when Kaposi sarcoma affects multiple parts of the body. For Kaposi sarcoma that's getting worse quickly, chemotherapy might help.