The dark or purple blotches associated with a person suffering from acquired immune deficiency syndrome are known as Kaposi's sarcoma, according to WebMD. Sarcomas are a rare kind of cancer that grow within connective skin tissue. Kaposi's sarcoma mainly affects the skin, mouth and the lymph nodes.
Kaposi's sarcoma can occur during any progressive period of the human immunodeficiency virus infection, explains WebMD. When a patient is diagnosed with AIDS, the latest stage of HIV infection, he becomes much more susceptible to outbreaks of Kaposi's sarcoma. However, Kaposi's sarcoma lesions are not life threatening and are a sign that the patient's immune system is being suppressed.