Kaposi's sarcoma (KS) is a cancer caused by infection with human herpesvirus 8 (HHV8). It causes purple, brown, or bluish-red tumours that look like sores on the skin. It may also affect the internal organs and the mucous membranes lining the mouth, nose, and anus.
Before HIV infection became widespread, Kaposi's sarcoma was uncommon and usually only found in elderly men, usually of Italian, Jewish, or African descent. It was also infrequently found in people who had received organ transplants and were taking immunotherapy to avoid organ rejection.
With the development of the HIV/AIDS epidemic KS became the most common cancer found in people with acquired immunodeficiency syndrome (AIDS), occurring as a complication of advanced HIV disease.
In people with HIV, the tumour grows and spreads more quickly than in elderly men without HIV. As HIV infection has now become better controlled, KS is once again becoming an infrequent condition.
The most likely cause of Kaposi's sarcoma is infection with HHV8 combined with the weakening of defense mechanisms that normally prevent this virus from multiplying.
This condition is most prevalent among sexually active men who have sex with men, The improvement in the medical treatment of HIV has drastically reduced the number of people developing this condition.
Symptoms and Complications
As HIV/AIDS became more prevalent, doctors became more aware of the appearance of Kaposi's sarcoma lesions. Sometimes, the appearance of the lesions is the first clue that the person may have advanced HIV infection.
Kaposi's sarcoma can appear as bluish-red, brown, or purple spots or lesions on the skin, which can be flat or slightly raised. The lesions can develop anywhere on the body but are most often found on the face (especially the ears, mouth, and tip of the nose), legs and feet, and genital area. For those with dark-coloured skin, the lesions may appear dark brown or black. The lesions generally aren't itchy or painful.
Kaposi's sarcoma may also appear as lesions on the palate (roof of the mouth), tongue, gums, or tonsils, or as gastrointestinal (stomach or intestine) lesions that bleed. There may also be lesions on the lungs, which may look like an infection or other forms of lung cancer. KS can also involve other organs in the body, such as the liver, spleen, or brain.
Other symptoms connected with Kaposi's sarcoma include:
- pain near the lesions
- swelling of the arms or the legs near the lesions
- shortness of breath or difficulty breathing
- blood in the sputum
- swollen lymph nodes
Kaposi's sarcoma can recur easily, despite treatment and remission, particularly if the person’s immune function worsens. If the lesions remain isolated on the skin, Kaposi's sarcoma can be painful and/or disfiguring, but isn't a life-threatening illness. If, however, it spreads to the inner organs, including the lungs, brain, and gastrointestinal tract, Kaposi's sarcoma can be fatal.
The appearance of Kaposi's sarcoma in a person with AIDS is often a sign that the disease is progressing. On the other hand, as the HIV infection is successfully treated and immune function is restored, the
Kaposi’s sarcoma lesions will often start to go away.
Making the Diagnosis
The lesions associated with Kaposi's sarcoma can often be mistaken for other disorders, such as benign fungal infections; other infection; or another type of cancer, non-Hodgkin's lymphoma. For that reason, your doctor will need to take a thorough medical history, asking questions about lifestyle and sexuality. He or she may recommend you have a test for HIV. After a physical exam, a skin biopsy is usually done.
A punch biopsy takes a small piece of tissue, while an excisional biopsy will remove the whole lesion. If many lesions are present, several of these might be tested just to verify that they are all the same. An excisional biopsy might be performed if there are only one or two small lesions.
Other tests might include:
- an oral exam, to check for lesions on the palate, tongue, gums, or tonsils
- a rectal exam, to check for lesions in the anus
- endoscopy, done with a flexible tube (affixed with a tiny light and a camera) that looks at the linings of the esophagus and stomach
- sigmoidoscopy, which involves using an endoscope or sigmoidoscope to view the lining of the rectum and colon
- chest X-rays, to check for lung lesions
- computed tomography (CT) imaging, which looks for lesions or other abnormalities
- bronchoscopy, which uses a thin tube used to look inside the lungs
- lung biopsy, a sample taken by your doctor for microscopic examination if bronchoscopy shows lesions in the lungs
Treatment and Prevention
Treatment of KS mainly involves treating the underlying condition that damaged the immune system in the first place. In the case of HIV/AIDS, this involves administration of combination anti-HIV medications that can suppress the HIV virus and allow restoration of immune function.
For people whose immune function cannot be restored (such as those who have had organ transplantation or are receiving cancer chemotherapy) or those rare individuals in whom no cause for immune suppression can be identified, KS is treated by physical removal of the tumour or lesion (cryotherapy in this case), chemotherapy, radiation, or a combination. When internal organs are affected, medications such as alpha interferon or medications used in the treatment of cancer such as liposomal anthracyclines or paclitaxel are occasionally used.
Because Kaposi's sarcoma is likely caused by an interaction between immune suppression and exposure to the sexually transmitted infection HHV8, the precautions taken against other sexually transmitted infections should also be taken to try to prevent Kaposi's sarcoma.
Practicing safer sex can also protect you from becoming infected with HIV, the virus that causes HIV/AIDS. Since HIV infection increases the risk of Kaposi's sarcoma, practicing safer sex can help reduce your risk of this cancer.
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