What is Kaposi sarcoma?
It's a cancer that begins in cells known as endothelial cells. These cells line the lymph or blood vessels under the skin or in mucous membranes, including in the skin, lung, liver, digestive tract (gut) and the lining of the mouth and nose.
Kaposi sarcoma is different from other types of cancer because of the way it develops. Other types of cancers begin in one place and can spread to other parts of the body if left untreated. However, Kaposi sarcoma can develop in several parts of the body to begin with. The most common site for it to develop is as external lesions on the skin but it can also affect internal organs such as the lymph nodes, liver, lungs, bowel, spleen and gut.
See also our pages on other soft tissue sarcomas, which are treated differently from Kaposi sarcoma.
Types of Kaposi sarcoma
There are four main types of Kaposi sarcoma:
- AIDS-related Kaposi sarcoma is the most common type and grows faster than the other types. It's associated with HIV infection. People with HIV who also have human herpes virus 8 (HHV8) have very weakened immune systems. This puts them at higher risk of developing Kaposi sarcoma.
- Classic Kaposi sarcoma is slow growing and rare. It's only found on the skin. In its early stages it doesn't usually cause any problems apart from the appearance of lesions on the skin. If you need treatment it's usually with radiotherapy or freezing the lesions off.
- Transplant-related Kaposi sarcoma is also rare. It's most common in people who have weakened or damaged immune systems, such as those who have an organ transplant. This happens because of the medicines (e.g. steroids) they need to take suppress their immune system
- Endemic or African Kaposi sarcoma is faster growing than classic Kaposi sarcoma and found mainly in people living in certain parts of Africa. Chemotherapy is the treatment for this type.
How common is Kaposi sarcoma?
Kaposi sarcoma is rare. About 26 people are affected by this cancer each year in Victoria. Kaposi sarcoma is more common in men than women.
Risks and causes of Kaposi sarcoma
Most cases of Kaposi sarcoma are caused by the human herpes virus 8 (HHV8). It's rare so most people who have HHV8 will never develop Kaposi sarcoma. It's more likely to develop in people who have HHV8 and their immune system is weakened, for example by human immunodeficiency virus (HIV). Most cases of Kaposi sarcoma in Australia are found in people who are HIV positive. We don't yet understand how HIV causes Kaposi sarcoma to grow.
Symptoms of Kaposi sarcoma
People with Kaposi sarcoma on the skin (including inside the mouth) may have one or more red, purple, pink or brown skin lesions on the legs and feet. They may be a single lesion or lesions in several places. They may appear reddish-purple or reddish-brown. The lesions can be slightly raised (nodule like) or they can appear flat. The lesions can grow quickly and they may later grow in other places, such as the stomach, bowel, or lymph nodes. They may grow in size and number over 10 years or more.
When the tumours grow in the digestive tract, they can cause nausea and sickness as well as possible bleeding. In the lungs, Kaposi sarcoma can cause breathlessness and a cough.
If the lymph nodes are affected they can become swollen. The swelling is caused by the build-up of fluid that begins to block lymph nodes in the arms and legs. This condition is called lymphoedema.
Other symptoms can include tiredness and energy loss (fatigue), night sweats and weight loss.
If you have one of these symptoms, but haven't been diagnosed with Kaposi sarcoma, remember that it's rare, and your symptom is likely to be due to something else. However, see your doctor if you have any symptom that persists for more than 2 weeks.
If you have one of these symptoms, but haven't been diagnosed with this cancer, remember that it's rare, and your symptom is likely to be due to something else. However, see your doctor if you have any symptom that persists for more than two weeks.
Expert content reviewers:
Annie Angle cancer nurse, Diploma Oncology Nursing, Royal Marsden, London