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Harvard Medical School

Kaposi's Sarcoma

What Is It?

Kaposi's sarcoma is a type of cancer caused by a virus called human herpes virus 8. The tumors of Kaposi's sarcoma appear as red or purple patches on the skin, mouth, lungs, liver or gastrointestinal tract. First described in 1872, it was considered a rare and relatively harmless tumor until the AIDS epidemic began. The more aggressive form of the disease, which occurs in people with severely weakened immune systems, is called AIDS-related Kaposi's sarcoma. With the explosion of HIV/AIDS, AIDS-related Kaposi's sarcoma has become far more common than the other types.

The four types of Kaposi's sarcoma are:

• Classic Kaposi's sarcoma — A rare, slow growing skin tumor, usually affecting males of Italian or Eastern European Jewish ancestry.

• African Kaposi's sarcoma — Though extremely rare in the rest of the world, Kaposi's sarcoma occurs more frequently among young males in certain countries in equatorial Africa. Usually it is a slow-growing tumor, but in some cases, the skin tumors can be aggressive, invading bone and tissue under the skin.

• Immunosuppressive-treatment-related Kaposi's sarcoma — People who are taking immunosuppressive drugs after an organ transplant may develop this form of Kaposi's sarcoma. It sometimes improves if the immunosuppressive medication is reduced or changed.

• AIDS-related Kaposi's sarcoma — This disease affects people with late-stage HIV/AIDS. It usually appears as a rapidly progressing tumor affecting the skin, lymph nodes, gastrointestinal tract, lungs, liver and spleen. In the United States, 95% of the cases involve homosexual or bisexual men. The incidence of this tumor is decreasing with the advent of highly active retroviral therapy for HIV/AIDS.