Kaposi sarcoma is a disease in which malignant tumors (cancer) can form in the skin, mucous membranes, lymph nodes, and other organs.

Kaposi sarcoma is a cancer that causes lesions (abnormal tissue) to grow in the skin; the mucous membranes lining the mouth, nose, and throat; lymph nodes; or other organs. The lesions are usually purple and are made of cancer cells, new blood vessels, red blood cells, and white blood cells. Kaposi sarcoma is different from other cancers in that lesions may begin in more than one place in the body at the same time.

Human herpesvirus-8 (HHV-8) is found in the lesions of all patients with Kaposi sarcoma. This virus is also called Kaposi sarcoma herpesvirus (KSHV). Most people infected with HHV-8 do not get Kaposi sarcoma. Those infected with HHV-8 who are most likely to develop Kaposi sarcoma have immune systems weakened by disease or by drugs given after an organ transplant.

There are several types of Kaposi sarcoma, including:

• Classic Kaposi sarcoma.
• African Kaposi sarcoma.
• Immunosuppressive therapy–related Kaposi sarcoma.
• Epidemic Kaposi sarcoma.
• Nonepidemic Kaposi sarcoma.

Tests that examine the skin, lungs, and gastrointestinal tract are used to detect (find) and diagnose Kaposi sarcoma.

The following tests and procedures may be used:

• Physical exam and history: An exam of the body to check general signs of health, including checking skin and lymph nodes for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken.
• Biopsy: The removal of cells or tissues so they can be viewed under a microscope by a pathologist to check for signs of cancer.
• Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body. This is used to find Kaposi sarcoma in the lungs.
• Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. An endoscope is inserted through an incision (cut) in the skin or opening in the body, such as the mouth. An endoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of disease. This is used to find Kaposi sarcoma lesions in the gastrointestinal tract.
• Bronchoscopy: A procedure to look inside the trachea and large airways in the lung for abnormal areas. A bronchoscope is inserted through the nose or mouth into the trachea and lungs. A bronchoscope is a thin, tube-like instrument with a light and a lens for viewing. It may also have a tool to remove tissue samples, which are checked under a microscope for signs of cancer.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis (chance of recovery) and treatment options depend on the following:

• The type of Kaposi sarcoma.
• The general health of the patient, especially the patient's immune system.
• Whether the cancer has just been diagnosed or has recurred (come back).