What Causes Kaposi Sarcoma?

Medically Reviewed on 2/11/2021

What causes Kaposi sarcoma?

Kaposi carcoma (KS) is a form of cancer caused by herpesvirus infection. Kaposi sarcoma is caused by immune suppression, HIV infection and certain socioeconomic factors.
Kaposi carcoma (KS) is a form of cancer caused by herpesvirus infection. Kaposi sarcoma is caused by immune suppression, HIV infection and certain socioeconomic factors.

Kaposi sarcoma (KS) is a form of cancer caused by herpesvirus infection. This virus is known as Kaposi sarcoma-associated herpesvirus (KSHV) or human herpesvirus 8 (HHV-8). The causes may include

  • Most people with this virus do not develop KS unless their immune system is suppressed. KS is rare in the United States and strongly associated with human immunodeficiency viruses (HIV) infection.
  • People with weaker immune systems are at risk of KS, including individuals who are taking medication to suppress the immune system after an organ transplant.
  • It can be spread both sexually (even through saliva) and nonsexually, including via organ transplantation and breastfeeding. However, infection appears to be more easily spread through certain types of sexual activity, including oral-anal contact, oral-genital contact and deep kissing.
  • The other factors for Kaposi sarcoma infection may include
    • Unhealthy rural residency
    • Lower socioeconomic status
    • Countries where malaria is common

Like all herpesviruses, KSHV remains in our body for the rest of one’s life. If the immune system becomes weak in the future, this virus may have the chance to reactivate, causing symptoms.

What is Kaposi sarcoma?

Kaposi sarcoma is a cancer of the blood vessels or lymph system. Kaposi sarcoma is considered an acquired immune deficiency syndrome (AIDS) defining illness. This means that when it occurs in someone infected with HIV, then the person officially has AIDS (and is not just HIV-positive). The most common form of Kaposi sarcoma is associated with infection by the human immunodeficiency virus (HIV), the virus that causes AIDS. The AIDS-related version of Kaposi sarcoma can be aggressive if it is not treated. Non-HIV related Kaposi sarcoma is rare. The symptoms of Kaposi sarcoma are

  • It is known for producing reddish or purple plaques on the skin. Kaposi sarcoma typically presents as purple or red patches or lesions made up of cancer cells, blood vessels and blood cells. The tumors may develop anywhere on the body and they often look like purple, red or brown skin blotches.
  • It can form sores on the skin, spread to the lymph nodes and, sometimes, involve the gastrointestinal tract, lungs, heart and other organs.
  • The lesions may grow in the skin, lymph nodes, internal organs and the lining of the mouth, nose and throat.
  • Other common signs and symptoms may include
    • Unexplained cough
    • Chest pain
    • Fever of unknown origin
    • Stomach pain
    • Intestinal pain
    • Diarrhea and/or blockage of the digestive tract
    • Lesions on the groin or legs, which block the flow of fluid out of the legs. This can lead to painful swelling.
    • Patients may experience sores due to skin break down. Lesions in the digestive tract can cause internal bleeding. Signs of gastrointestinal bleeding are black or tarry stool
    • If lesions develop in the lungs, the person may have shortness of breath or they may cough up blood.


There are four types of KS based on the groups of people who are infected

  1. Classic KS: Mainly affects older men of Eastern European, Middle Eastern and Mediterranean descent. The disease usually develops slowly.
  2. Epidemic (AIDS-related) KS: Occurs most often in people who have HIV infection and have developed AIDS.
  3. Endemic (African) KS: Mainly affects people of all ages in Africa, who are already immunocompromised and develop malaria as well.
  4. Immunosuppression-associated or transplantation-associated KS: Occurs in people who have had an organ transplant and are on medicines that suppress their immune system.


  • Although the diagnosis is suspected from the appearance of lesions and the patient’s risk factors, a definite diagnosis can be made only by tissue biopsy and microscopic examination. The extent of the disease may be determined by medical imaging.


  • KS is not curable, but it can often be treated for many years. Treatment is based on the subtype, the speed of growth, whether the disease is localized or widespread and the patient’s immune function.
  • Treating HIV-infected patients with a so-called cocktail of highly active antiretroviral therapy (HAART) has dramatically lowered the incidence of Kaposi sarcoma in the United States. 
  • In tumors associated with immunodeficiency or immunosuppression, treating the cause of the immune system dysfunction can slow or stop the progression of the disease.
  • The other treatments may include
    • Antiviral therapy against HIV, since there is no specific therapy for HHV-8
    • Combination chemotherapy
    • Freezing the lesions

Treating KS does not improve the chances of survival from HIV/AIDS. The outlook of patients with KS depends on the person's immune status and how much of the HIV is in their blood (viral load). If HIV is controlled with medicine, the lesions often shrink away on their own.

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Medically Reviewed on 2/11/2021
Medscape Medical Reference