A herpes virus called Human Herpes Virus 8 (HHV-8) has shown to cause AIDS-related KS. However, not everyone who has HIV and HHV-8 develops KS. One study found that the presence of HHV-8 in both blood cells and saliva was associated with KS, while patients who only had HHV-8 in their saliva were much less likely to develop KS.
In a recent study, men who had HHV-8 were nearly 12 times more likely to develop KS than men who did not have HHV-8. For unknown reasons, men who have sex with men are the most likely to develop the herpes infection. Therefore, men are more likely than women to develop KS.
Early in the AIDS epidemic, doctors saw a sudden appearance of KS. This is because HIV and AIDS patients have a weakened immune system, and their ability to fight against disease and infection is impaired. HHV-8 is usually dormant in healthy individuals. However, immunocompromised patients, including HIV/AIDS patients, may develop KS as a result of the infection.
It has also been suggested that KS may sometimes be caused by an overactive immune system. HIV infections activate T-cells, which secrete a growth factor called oncostatin M. Increased levels of oncostatin M. may stimulate the growth of early KS cells, which may eventually become cancerous. However, further research is needed to confirm this theory.
Once the KS cells have developed in one part of the body they can enter the bloodstream and lodge in other tissues, which causes additional lesions.
According to the CDC, KS is considered an AIDS-defining disease. This means that when HIV-infected patients develop KS, their condition has progressed to AIDS.
Symptoms of AIDS-related KS vary from minimal skin involvement to widespread organ involvement.
Common symptoms include skin lesions that may erupt at many places on the body, including on the skin (raised lumps that may be purple, brown or red), in the mouth, on the lymph nodes and other organs (especially organs in the gastrointestinal tract, lungs, liver and spleen). Most patients experience enlarged lymph nodes and unexplained fever or weight loss. Sometimes patients experience painful swelling, especially in the legs, groin area or skin around the eyes.
While the skin lesions may be disfiguring, they are not usually life threatening. In some cases, the lesions may be painful or cause swelling. If KS develops in the lungs, liver or gastrointestinal tract, however, the disease may be life threatening, causing internal bleeding or difficulty breathing.
General: Several tests, including chest X-rays, thallium or gallium scans, as well as a bronchoscopy, esophagogastroduodenoscopy (EGD) or colonoscopy, may indicate KS. However, a tissue biopsy is the only definitive diagnostic test for KS.
Biopsy: A biopsy is the only definitive diagnostic test for KS. During the procedure a sample of tissue is analyzed under a microscope for cancerous cells. The tissue sample may be taken from the skin (punch biopsy), gastrointestinal tract (endoscopic biopsy), tissue that lines the lungs and the inside of the chest wall, (pleural biopsy) or lung tissue (transbronchial biopsy).
Chest X-ray: Chest X-rays provide variable and nonspecific results. They may detect abnormal tissue growth, enlarged lymph nodes or an isolated pulmonary nodule (oval-shaped sore (lesion) in the lungs.
Thallium or gallium scans: Thallium or gallium scans may help a healthcare provider distinguish KS from an infection. Thallium or gallium is injected into the patient before an X-ray is taken. KS lesions in the lungs usually demonstrate intense thallium uptake and no gallium intake. Infections, on the other hand, do not uptake either substance.
Bronchoscopy: A bronchoscopy may be used to determine if there is pulmonary involvement. During the test, a bronchoscope (thin, flexible tube with a camera) is inserted into the esophagus, through the mouth. The test allows the healthcare provider to look inside the lungs. If KS is in the lungs, a slightly raised, red lesion will be visible. However, a biopsy is generally avoided because there is a risk of bleeding.
Esophagogastroduodenoscopy (EGD) or colonoscopy: A qualified healthcare provider may observe the gastrointestinal tract during an esophagogastroduodenoscopy or colonoscopy test. During the procedure, an endoscope (thin, flexible tube with a camera) is either inserted through the mouth (esophagogastroduodenoscopy) or the anus (colonoscopy) to view the gastrointestinal tract. The physician looks for gastrointestinal lesions, which are frequently observed in KS patients. In addition, the physician may insert a biopsy needle into the endoscope to remove a small tissue sample. The sample is then analyzed under a microscope for cancerous cells.