Kaposi's sarcoma. Image 1 of 2. Flat nodular plaque caused by Kaposi's sarcoma on the tongue of a patient with AIDS. AIDS (acquired immune deficiency syndrome) is a disease caused by the human immunodeficiency virus (HIV). It causes a gradual weakening of the immune system, making otherwise harmless infections life-threatening. Kaposi's sarcoma is a type of skin cancer. In AIDS it often spreads to other tissues and can be rapidly fatal. Despite this, it responds well to chemotherapy. This image was taken in Africa, where lack of access to medicine and information makes AIDS a major public health concern. For the tongue after chemotherapy, see image M112/317.