What is Kaposi sarcoma?
Kaposi sarcoma is a cancer that develops in the walls of blood vessels and lymph vessels (the channels supporting the immune system). These tumor-forming soft tissue sarcomas are often tied to the human immunodeficiency virus (HIV). They’re found most often in the skin—making them an unusual skin cancer—or the linings of the mouth, nose, and anus.
Sometimes, Kaposi sarcoma is more disseminated (widespread) in the body, making it harder to treat and often posing a greater health threat. Unlike many other cancers, it doesn’t necessarily metastasize (spread) to these additional sites in the body from a single tumor. Instead, without treatment, tumors can quickly develop in multiple places in the body, including the lymph nodes, lungs, liver, spleen, and gastrointestinal (GI) tract.
Kaposi sarcoma is a rare cancer—thanks to the development of drugs to treat HIV and AIDS, the number of Kaposi sarcoma cases has fallen in the U.S. Each year, roughly six people per million are now diagnosed with it. Globally, the total annual figure is about 34,000.
The Sarcoma Program and AIDS-Related Oncology Program at Penn Medicine's Abramson Cancer Center work together to care for people with Kaposi sarcoma. Together, these teams are among the nation’s most experienced in treating this rare cancer and have cared for people with Kaposi sarcoma since the early days of the HIV/AIDS epidemic.
Types of Kaposi sarcoma
This type of Kaposi sarcoma is the most common. Because HIV infections make people more likely to also develop HHV-8, epidemic Kaposi sarcoma is considered connected to the HIV epidemic. Developing a Kaposi sarcoma is one of the signs that HIV infection has turned into AIDS. Epidemic sarcoma also has the potential to develop widely across the body. Fortunately, effective drug therapy for HIV has resulted in fewer cases of Kaposi sarcoma. If you do develop Kaposi sarcoma, HIV drugs can stop it from progressing.
Some people with HHV-8 develop Kaposi sarcoma because their immune systems are weakened due to factors including autoimmune disease or immune-suppressing drugs taken after organ transplant. Roughly 1 in 200 U.S. transplant patients develop Kaposi sarcoma. It usually is limited to the skin but sometimes becomes widespread.
This form is mainly found in older people of Mediterranean, Eastern European, or Middle Eastern descent. It is more common in men than women. Researchers believe these people have genetic changes that make them more vulnerable to HHV-8. As they age, their immune systems also naturally grow weaker, raising Kaposi sarcoma risk. Classic-type tumors tend to grow less quickly and widespread disease is less likely.
Most cases of endemic Kaposi sarcoma are found in Africa, where HHV-8 infection rates are much higher and other common diseases weaken the immune system. It can affect children and adults, mostly under 40 years old. Endemic Kaposi sarcoma typically does not grow beyond the skin.
Signs and symptoms of Kaposi sarcoma
Kaposi sarcoma typically starts as small, flat patches on the skin or inside the mouth. These patches may be red, purple, pink, brown, black, or blue and look like bruises. They don’t usually cause pain at first but can turn into bumps as they grow and may form open wounds.
More widespread Kaposi sarcoma can cause:
- Bleeding or blockage in the digestive tract
- Breathing trouble
- Chest pain
- Diarrhea
- Fever
- Coughing up blood
- Gastrointestinal pain
- Lymphedema, or painful swelling in certain tissues
- Nausea and vomiting
- Severe sweating while sleeping
- Unintended weight loss
What causes Kaposi sarcoma?
Unlike many other soft tissue sarcomas, doctors do know the cause of Kaposi sarcoma—a virus called human herpesvirus 8 (HHV-8). The virus spreads through sex, saliva, and childbirth. Researchers believe the virus changes instructions for how certain cells grow, making them grow out of control and form tumors.
HHV-8 infections are uncommon in the U.S. and people with the virus don’t necessarily develop Kaposi sarcoma. The cancer only seems to form when people have a weakened immune system or have inherited genetic changes that make them more vulnerable.
Finding and diagnosing Kaposi sarcoma
Diagnosis begins with a discussion of your symptoms and an exam of areas where Kaposi sarcoma commonly develops, including the skin, mouth, nose, anus, and nearby lymph nodes.
If Kaposi sarcoma is suspected, your provider may recommend blood tests to evaluate your immune system and check for HIV if it hasn’t already been diagnosed. Additional testing can help determine whether the cancer has spread to other parts of the body or affected internal organs.
A tissue biopsy confirms the diagnosis. Together, the exam, biopsy, blood tests, and imaging results help determine the extent of the disease and guide
Managing Kaposi sarcoma
Kaposi sarcoma is often treatable, although therapy may not always cure the cancer, and it can recur (return). Recommendations for sarcoma treatment depend on how far the cancer has spread, how well your immune system is functioning, and whether you have HIV-related health conditions.
For epidemic Kaposi sarcoma, treatment often begins with medicines that control HIV. In many people, these medicines shrink tumors and may be all that’s needed.
Surgery may be considered for small, visible tumors that are limited in number. However, because Kaposi sarcoma can return after surgery, other approaches are often recommended first.
If additional care is needed, your provider may recommend one or more therapies based on the number, size, and location of the tumors. Researchers also continue to study new approaches through clinical trials to improve care for people with Kaposi sarcoma.
Working together to treat Kaposi sarcoma
Kaposi sarcoma can affect many parts of the body and is closely linked to the immune system, making coordinated care especially important. At Penn Medicine, specialists in sarcoma, infectious diseases, HIV oncology, medical oncology, pathology, radiology, and other fields work together to evaluate each case and recommend the most effective approach.
Our involvement in sarcoma research and clinical trials helps expand treatment options for people with Kaposi sarcoma and other rare soft tissue sarcomas. By combining expertise across specialties with ongoing research, we're working to improve care today while helping shape tomorrow's treatments.
Rated “exceptional” by The National Cancer Institute
Penn Medicine’s Abramson Cancer Center is a world leader in cancer research, patient care, and education. Our status as a national leader in cancer care is reflected in our continuous designation as a Comprehensive Cancer Center by the National Cancer Institute (NCI) since 1973, one of 7 such centers in the United States. The ACC is also a member of the National Comprehensive Cancer Network, one of a select few cancer centers in the U.S., that are working to promote equitable access to high-quality, advanced cancer care.