Kaposi sarcoma, or KS, is a type of cancer. It was one of the first diseases seen in people with AIDS and remains one of the most common cancers in HIV-positive people.

Most researchers now agree that a virus called Kaposi sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus-8 (HHV-8), causes KS. However, the virus alone is not enough to cause KS. Abnormalities of the immune system, such as in people with AIDS, may allow the virus to cause disease.

Approximately 30 percemt of all HIV-positive gay and bisexual men are infected with KSHV, whereas only two to three percent of HIV-positive transfusion recipients or hemophiliacs are infected with the virus. As for HIV-positive heterosexual women, only three to four perecent are infected with KSHV.

KS has been known to occur in some HIV-positive people with relatively high T-cell counts (around 500 cells/mm3). The risk of developing KS, especially in people infected with both HIV and KSHV, increases the more the immune system becomes damaged and suppressed. Luckily, anti-HIV therapy has permitted many HIV-positive people to keep their immune systems healthy and, in turn, prevent KS from occurring in the first place.


What are the symptoms?

KS blotches, called tumors or lesions, range in color from pinkish-red to brownish-blue. The lesions are usually flat, painless, and do not blanche—turn white—when pressure is applied to them (unlike bruises). KS lesions on the skin are not usually life threatening. However, they can be emotionally troubling, particularly when they occur on the face. Over time, these lesions may become elevated, more noticeable, and painful.

Some people may only experience one lesion, perhaps on their leg, but not anywhere else. Some people with KS may see new lesions occur very slowly, on the order of one every few months; others may experience several new lesions every week. Generally speaking, the more suppressed the immune system becomes, the more likely it is that new lesions will occur.

KS lesions inside the mouth can make eating difficult and painful. Lesions in the gut, particularly in the large intestine and the colon, can cause diarrhea, cramping, and bleeding. KS of the lungs (pulmonary KS) can cause severe breathing problems and discomfort. KS lesions in the gut and in the lungs can be fatal if not treated or controlled.


How is KS diagnosed?

Even though researchers can now check for KSHV in blood samples, no test is routinely available to health care providers. Even if these tests were widely available, it’s important to note that being infected with KSHV does not mean that KS will occur, even if the immune system becomes suppressed.

KS lesions on the skin are usually diagnosed by biopsy. To conduct a biopsy, a health care provider—either a primary-care doctor, an oncologist, a dermatologist, or a surgeon— takes a small piece of the lesion and has it examined in a laboratory. The report generated by the lab will determine what kind of tumor it is.

To diagnose pulmonary KS, a scope—called a bronchoscope—can be passed down the windpipe into the lungs to determine if lesions are present. X-ray can also be used to check the lungs for KS.

KS of the gut is usually diagnosed using scopes placed down the back of the throat or through the rectum (endoscopy). KS in the gut has a unique appearance, thus a biopsy is usually not necessary.


How is KS treated?

KS lesions of the skin, because they are not usually life threatening, do not necessarily need to be treated. While a number of good localized therapies exist—that is, therapies applied directly to the skin to treat certain lesions—they are generally not effective in preventing new lesions from occurring. And while systemic therapy—drugs taken by mouth or through an intravenous (IV) line—can both treat existing lesions and prevent new ones from occurring, they can cause serious side effects.

KS lesions in the gut and in the lungs require systemic therapy. Without treatment, these lesions can cause serious illness.

No treatment is 100 percent effective, 100 percent of the time. In most studies, only a minority of patients actually see their KS lesions disappear completely. Some patients may not see their lesions disappear, but may see a dramatic improvement in their size, shape, color, and bulkiness; others may not experience any noticeable changes, but may stop new lesions from developing.


Some of the most common local (topical) therapies include:

  • Alitretinoin (Panretin): The only topical treatment actually tested in clinical trials and approved by the Food and Drug Administration (FDA) for skin KS lesions. This gel is applied to lesions three or four times a day, and has been shown in studies to be effective.
  • Cryotherapy: Liquid nitrogen is applied to the lesion. This kills the cells in the lesion and promotes healthy skin cells to grow in its place. Good for small lesions.
  • Radiation therapy: For lesions that are raised, relatively large, or deep in the skin, radiation-or electron-beam therapy-provides good results. Radiation therapy is often recommended for KS lesions on the penis or the feet, given that other local therapies can be painful when used on these two parts of the body.
  • Intralesional therapy: Some tumors, such as those inside the mouth, can be treated locally using a small amount of chemotherapy and a hypodermic needle.
  • Vinblastine (Velban): a chemotherapy drug usually administered through an IV line, can be injected directly into the lesion.

Some of the most common systemic (IV or oral) therapies include:

  • Antiretroviral therapy (HAART): Considering the profound impact anti-HIV therapy has on viral load and T-cell counts, many HIV-positive people with KS often see their lesions improve while on therapy. Sometimes the effect is dramatic, other times anti-HIV therapy may prevent new lesions from forming. Antiretroviral therapy is often used in combination with other systemic therapies to enhance effectiveness.
  • Interferon-alfa (Roferon-A, Intron A): This drug mimics a naturally occurring protein in the body. It is active against HIV, helps restore immune function, and has been shown to be an effective treatment for KS. Interferon-alfa can cause side effects, and is best used in patients who have relatively high T-cell counts (greater than 200 cells/mm3) before starting therapy.
  • Liposomal chemotherapy (Doxil or DaunoXome): These drugs represent a new form of standard chemotherapy drugs. Each dose of these drugs contains millions of microscopic spheres of fat, each sphere containing the active drug. This increases the amount of drug in the blood, thus increasing the amount of drug in each lesion. Some research shows that liposomal chemotherapy is more effective—and less toxic—than standard chemotherapy.
  • Intralesional therapy: Some tumors, such as those inside the mouth, can be treated locally using a small amount of chemotherapy and a hypodermic needle.
  • Standard chemotherapy (doxorubicin, vincristine, bleomycin, etoposide, paclitaxel): Several studies have examined these drugs, both used as monotherapy and in combination with each other, and have reported varying degrees of success. Combination therapy—particularly bleomycin in combination with vincristine, with or without doxorubicin—has been shown to be more effective than monotherapy. However, side effects are more common in patients taking two or more chemotherapy drugs at the same time.

Can KS be prevented?

No, not at the present time. However, using drugs to prevent KS may be possible in the near future. Given that KSHV has been shown to be a major culprit in the development of KS lesions, researchers are now looking at various antiviral drugs to see if they are effective against this virus. HIV-infected patients who are infected with KSHV and have low CD4+ cell counts may benefit greatly from these drugs, as they may prevent KS lesions from occurring in the first place.


Are there any experimental treatments?

Yes, several. Over the past few years, researchers have learned a lot about KS, including the way KSHV causes lesions and the way in which lesions form. This has allowed for the development of several promising drugs, some of which are now in clinical trials.

If you would like to find out if you are eligible for any clinical trials that include new therapies for the treatment or prevention of KS, visit ClinicalTrials.gov, a site run by the U.S. National Institutes of Health. The site has information about all HIV-related clinical studies in the United States. For more info, you can call their toll-free number at 1-800-HIV-0440 (1-800-448-0440) or email contactus@aidsinfo.nih.gov.

Last Reviewed: January 18, 2016