Kaposi's sarcoma is an uncommon cancer that can affect both the skin and the internal organs, Memorial Sloan Kettering Cancer Center explains. Human herpesvirus 8 causes it but usually only in cases where the immune system is especially vulnerable to the virus. Examples of these are cases of HIV infection or people with a genetic predisposition to human herpesvirus 8, primarily people of Eastern European, Middle Eastern or Mediterranean descent.
The symptom of Kaposi's sarcoma most people notice first are flat small discolored patches on the skin or on the inside of the mouth, says Memorial Sloan Kettering Cancer Center. These patches are generally painless and purple or red in color and look similar to bruises. When Kaposi's sarcoma affects internal organs, possible symptoms include shortness of breath, coughing up blood, and uncomfortable swelling in the legs or arms. Other possible symptoms of internal Kaposi's sarcoma include rectal bleeding, stomach pain and diarrhea.
Kaposi's sarcoma usually grows relatively slowly in people who have an inherited vulnerability, but it can be much more aggressive in people with HIV, according to Memorial Sloan Kettering Cancer Center. There is no cure for Kaposi's sarcoma, but with treatment, many patients experience relief from its symptoms.