What is cancer?
Cancer is when cells in the body change and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body does not need them any longer.
Cancer is made up of abnormal cells that grow even though your body doesn't need them. In most cancers, the abnormal cells grow to form a lump or mass called a tumor. If cancer cells are in the body long enough, they can grow into (invade) nearby areas. They can even spread to other parts of the body (metastasis).
What is Kaposi sarcoma?
In Kaposi sarcoma (KS), cancer develops from the cells that line lymph or blood vessels. KS gets its name from Dr. Moritz Kaposi, who first described it.
KS forms as purple, brown, or red patches just under the skin, in mucous membranes (like the inside of the nose, mouth, or anus), or in internal organs. These patches are called lesions. KS lesions can be deforming, but they are not usually life-threatening. In most cases, the lesions cause no symptoms. Sometimes, though, the lesions can cause pain or swelling of the skin. When KS involves organs such as the liver, lungs, digestive system, or lymph nodes, other symptoms can develop. For example, KS tumors in the lungs can cause breathing problems.
KS is linked to infection with human herpes virus 8 (HHV-8), also known as the Kaposi sarcoma-associated herpes virus (KSHV). This virus can cause certain types of cells to grow out of control, which might lead to cancer. However, most people infected with HHV-8 don't develop KS. KS appears most often in people infected with HHV-8 who also have a weak immune system.