Sarcoma – Kaposi

Approved by the Cancer.Net Editorial Board, 08/2023

Cancer begins when healthy cells change and grow out of control, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can grow and spread to other parts of the body. A benign tumor means the tumor can grow but will not spread.

Kaposi sarcoma is a type of soft-tissue sarcoma. Soft-tissue sarcomas are a group of cancers that begin in the tissues that support and connect the body. Kaposi sarcoma is caused by the human herpeseviris 8 (HHV-8); however, most people with HHV-8 infections never develop Kaposi sarcoma.

Kaposi sarcoma generally develops in tissue located below the skin’s surface or in the lining of the mouth, nose, or anus. Areas where tissues have abnormal changes are known as Kaposi sarcoma lesions. These lesions usually appear on the skin as raised blotches or nodules. They may be purple, red, blue, brown, or black. When viewed under a microscope, Kaposi sarcoma cells resemble blood vessels.

All Kaposi sarcoma is caused by HHV-8, but there are several named groups that are commonly used. The most important distinction for Kaposi sarcoma is whether the person has a weakened immune system.

• Classic Kaposi sarcoma. Classic Kaposi sarcoma was first described in the late 1800s. It traditionally occurs in older men of Jewish or Mediterranean descent. Lesions most often appear on the lower body, particularly on the legs, ankles, or soles of the feet. Classic Kaposi sarcoma is more common in men than in women, and lesions may develop slowly over a period of 10 to 15 years.
• Epidemic Kaposi sarcoma. Kaposi sarcoma in people with HIV/AIDS is often called epidemic Kaposi sarcoma. Acquired immune deficiency syndrome (AIDS) is a disease of the immune system caused by infection with the human immunodeficiency virus (HIV). It is now the most common type of Kaposi sarcoma. Epidemic Kaposi sarcoma causes lesions to form in many different areas on the body. It may affect the lymph nodes and organs, such as the liver, spleen, lungs, and the digestive tract. Learn more about HIV/AIDS-related cancer.
• Acquired, or transplant-associated, Kaposi sarcoma. Acquired Kaposi sarcoma develops in people whose immune systems are depressed, typically due to taking drugs to suppress their immune system because of an organ transplant or an autoimmune disease. Because this treatment lowers the function of the immune system, additional diseases or infections can occur. Kaposi sarcoma is 150 to 200 times more likely to develop in people who have received an organ transplant than in people in the general population. Most of the time, acquired Kaposi sarcoma only affects the skin, but the disease can spread to the mucous membranes or other organs.
• Endemic Kaposi sarcoma. Endemic Kaposi sarcoma existed in equatorial Africa long before the presence of the HIV pandemic. People generally develop the disease at a younger age. It usually causes skin lesions without any other symptoms. A particularly aggressive form of endemic Kaposi sarcoma can develop in children who have not yet reached puberty. It usually involves the lymph nodes and other organs.