What Is Kaposi Sarcoma?

Kaposi sarcoma (KS) is a form of cancer that is caused by infection with a virus called the Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8).

In KS, tiny blood vessels grow below the surface of the skin and in the mouth, nose, eyes, and digestive tract. The tumors can also grow on the internal organs.

The tumors appear as patches or nodules on the skin and/or the mucous membranes. They can also spread to lymph nodes and lungs. KS is more common in men and in people with suppressed immune systems.

Learn more about the types of Kaposi sarcoma, causes, and treatments available.

Female doctor examining male patient with dermascope, looking for signs of skin cancer

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Types of Kaposi Sarcoma

There are four different types of KS. Each type is defined by the populations it develops in, although the changes within the KS cells in each type are similar.

Epidemic (AIDS-Associated) Kaposi Sarcoma

The most common type of KS in the United States is epidemic or AIDS-associated KS. This type of KS develops in people who have HIV (the virus that causes AIDS).

KS is considered to be an AIDS-defining illness, which means that if someone infected with HIV develops KS, that person officially has AIDS (as opposed to being only HIV-positive).

Before HIV/AIDS was widespread, Kaposi sarcoma was extremely rare in the United States, with about two people diagnosed for every 1 million people. At the height of the HIV/AIDS epidemic, the rate increased to about 47 people per 1 million people.

However, with more effective treatments for HIV/AIDS, the number has significantly decreased in recent years to about six cases per 1 million people.

Classic (Mediterranean) Kaposi Sarcoma

Classic Kaposi sarcoma is rare. It is more common in older men of Mediterranean, East Asian, or Jewish descent.

This type of KS is normally only found in the skin, particularly on the lower legs and feet. It is a slow-growing cancer.

Endemic (African) Kaposi Sarcoma

Endemic Kaposi sarcoma is most common in sub-Saharan Africa where HHV-8 is more common. It usually develops in younger people (under the age of 40).

Kaposi sarcoma-associated herpesvirus (KSHV) infection is much more common in Africa than in other parts of the world, making the risk of KS higher.

Iatrogenic (Transplant-Related) Kaposi Sarcoma

This type of KS develops in people who have had an organ transplant. In this situation, KS occurs because these patients need to take drugs that suppress their immune system.

By weakening the body’s immune system, the drugs increase the chance that someone infected with KSHV will develop KS.

Kaposi Sarcoma Symptoms

The symptoms of KS differ depending on which parts of the body are affected by the disease. If you have KS, you might have:

  • Slightly elevated purple, pink, brown, black, blue, or red blotches or bumps anywhere on the skin or in the mouth and/or throat (unlike bruises, they don't change color when you press on them)
  • Lymphedema (swelling caused by a blockage of the lymphatic system)
  • Unexplained cough or chest pain
  • Unexplained stomach or intestinal pain
  • Diarrhea and/or blockage of the digestive tract (which can be caused by Kaposi sarcoma lesions that have developed in the gastrointestinal system)

Sometimes, people with Kaposi sarcoma do not have any of these symptoms. In other cases, the cause of a symptom is from another medical condition and not cancer.

Causes

Kaposi sarcoma is caused by infection with Kaposi sarcoma-associated herpesvirus, also known as human herpesvirus 8.

KSHV is in the same family as the Epstein-Barr virus (EBV), the virus that causes infectious mononucleosis (mono). EBV has also been linked to several other types of cancer.

There are several factors that can raise a person’s risk of developing Kaposi sarcoma, including:

  • Ethnicity: People of Jewish or Mediterranean descent, as well as those living in sub-Saharan Africa, have a higher risk of developing Kaposi sarcoma.
  • Gender: Men have a higher risk of developing Kaposi sarcoma.
  • Human herpesvirus 8 (HHV-8): Also called the Kaposi sarcoma herpesvirus (KSHV), the HHV-8 virus can cause Kaposi sarcoma. However, most people with HHV-8 infection do not develop Kaposi sarcoma. KS most often occurs when a person with HHV-8 also has problems with the function of their immune system.
  • Immune deficiency: People with HIV/AIDS and people whose immune systems are suppressed after organ transplantation have a higher risk of developing Kaposi sarcoma.

KSHV can be transmitted through sexual contact. It can also spread through nonsexual routes, such as the transfusion of contaminated blood and tissues transplants or by saliva contact.

Diagnosis

If your doctor suspects you might have KS, they will ask you questions about your medical history, such as about any illnesses or operations that you've had, your sexual activity, and whether you have had any possible exposures to KSHV and HIV. Your doctor will also ask you about your symptoms, including if you've noticed any skin tumors.

If there are no visible symptoms of KS but your doctor thinks you may have it, more tests might be needed. Depending on where the suspected lesion is, several types of testing can be used to make a diagnosis.

  • A biopsy involves the removal of cells from the suspected site. Your doctor will send the sample to a lab for testing. Other tests can suggest cancer is present, but only a biopsy can make a definite diagnosis.
  • A chest X-ray can help your doctor look for signs of KS in the lungs.
  • An endoscopy is used to look at the inner lining of the esophagus, the stomach, and the first part of the small intestine. Your doctor can use a long, thin tube with a camera and a biopsy tool on the end to see the inside of the GI tract and take biopsies or tissue samples.
  • A bronchoscopy is a test that lets your doctor look in your windpipe (trachea) and the large airways of the lungs.

Treatment

KS treatment will need to be tailored to each patient. The treatment for KS depends on:

  • The type of KS you have
  • The number and size of lesions you have
  • Where the lesions are on your body
  • Your general state of health

For people with epidemic Kaposi sarcoma, antiretroviral treatment (ART) for HIV/AIDS is usually used before any other treatments to treat the tumor and reduce symptoms. ART can be given by itself or in combination with chemotherapy, depending on the spread of the disease and the symptoms that a person has.

Local treatment can be used if a person has only a few skin lesions. Examples of local treatment for KS include:

  • Surgery: KS surgery is most useful when the lesions are located in a single area or in a few specific areas. The lesions can either be removed by cutting them out or by freezing them with liquid nitrogen (cryosurgery).
  • Topical treatments: A topical treatment plan for KS may include skin creams to shrink or stop the growth of lesions. Topical creams often do not stop cancer completely, but they can improve its appearance.

KS tumors of the skin, mouth, or anus can often be treated with low doses of radiation therapy. Doctors typically use radiation therapy to relieve KS symptoms or treat highly visible lesions. Sometimes, radiation is given to patients who cannot have chemotherapy because they are too weak.

Prognosis

More effective treatments for HIV/AIDS are improving the survival rate for people with KS by treating the infections associated with HIV/AIDS as well as the tumors themselves.

The five-year survival rate for KS tells you the percentage of people who live at least five years after the cancer is found. The five-year survival rate for people with Kaposi sarcoma is 74%.

If KS has not spread, about 81% will live at least five more years. In people whose cancer has spread to nearby areas, the survival rate is 62%. The rate is 41% for people with cancer that has spread farther away.

Summary

Kaposi sarcoma is more common in people with suppressed immune systems and often occurs in people who have HIV. It is highly treatable if the cancer is found before it has spread (at which point a person has a survival rate of about 81%).

The key to reducing the risk of KS is early diagnosis and treatment of HIV. The initiation of ART at the time of diagnosis can maintain or restore healthy immune function while reducing a person's risk of developing KS.

A Word From Verywell

Some people with KS will notice growths that have appeared on their bodies (such as on their skin or in their mouth). However, if these tumors are inside the body, a person may not realize they have them. If they have other symptoms of KS and certain risk factors, like HIV or a suppressed immune system, their doctor can run tests to see if they have KS.

If you have HIV, know that advances in treatment for HIV/AIDs have reduced the risk of KS. Early diagnosis and treatment of HIV are important parts of reducing your risk of KS and improving your odds of survival if you do develop it.

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7 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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