Kaposi's sarcoma is a cancer that 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.
It was at one time the most common cancer found in people with acquired immunodeficiency syndrome (AIDS), and it occurs as a complication of AIDS. Men infected with the human immunodeficiency virus (HIV) are affected about 8 times as often as women with HIV. It is also more common among people taking immunosuppressive medications (e.g., organ transplant recipients).
Before AIDS became widespread, Kaposi's sarcoma was usually only found in elderly men, usually of Italian, Jewish, or African descent. It was also found in people who had received organ transplants and were taking immunotherapy to avoid organ rejection. In people with AIDS, the tumour grows and spreads more quickly than in elderly men without AIDS.
The most likely cause of Kaposi's sarcoma is the combination of immune suppression, as occurs with HIV infection, or immunosuppressant therapy after an organ transplant, and exposure to the human herpesvirus 8 (HHV 8), a sexually transmitted infection.
The condition is most prevalent among sexually active homosexual and bisexual males with HIV, and the improvement in the medical treatment of HIV appears to have reduced the incidence of this condition. The incidence of the condition in heterosexual people with HIV is far lower.
Symptoms and Complications
As 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 HIV or the condition it causes, AIDS.
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.
Other symptoms connected with Kaposi's sarcoma include:
- shortness of breath or difficulty breathing
- blood in the sputum
- swollen lymph nodes
Kaposi's sarcoma can recur easily, despite treatment and remission. It can also affect the lungs and liver.
If the lesions remain isolated on the skin, Kaposi's sarcoma isn't a life-threatening illness. If, however, it attacks the inner organs, including the lungs, brain, and gastrointestinal tract, Kaposi's sarcoma can be fatal.
The appearance of Kaposi's sarcoma among people who have AIDS is often a sign that the disease is progressing. Treatment and remission (absence of any signs or symptoms of the disease) of Kaposi's sarcoma doesn't help improve the prognosis of AIDS.
Making the Diagnosis
The lesions associated with Kaposi's sarcoma can often be mistaken for other disorders, such as benign fungal infections 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. The excisional biopsy is usually 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
- a barium enema, which allows doctors to track the progress of barium through the colon by using X-rays
- 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 – if bronchoscopy shows lesions in the lungs, your doctor can take a sample for microscopic examination
Treatment and Prevention
Treatment of Kaposi's sarcoma can be difficult due to the immunosuppressed state of many of the people who are affected. These people are at a high risk of infections from procedures. Your doctor will recommend treatment based on your general health as well as on where the lesions are, how extensive they are, and how many there are.
Generally, most cancers are treated by physical removal of the tumour or lesion (cryotherapy in this case), chemotherapy, radiation, or a combination. For people with AIDS, anti-HIV medications are used against the virus. This can improve the person's overall health and help treat Kaposi's sarcoma.
For skin lesions, some possible treatments are:
- cryotherapy: Cryotherapy is a procedure that uses liquid nitrogen or other cryogens to freeze tissue. In cases of Kaposi's sarcoma, a doctor might freeze the lesions to destroy them.
- locoregional therapy: Locoregional therapy involves injecting chemotherapy agents directly into the Kaposi's sarcoma lesions.
- radiation therapy: Direct radiation therapy is another option to treat for the lesions. This involves aiming radiation directly at the spots. Some side effects associated with radiation include:
- red, dry skin at the radiation site
- nausea and vomiting
- decreased appetite
If the Kaposi's sarcoma has advanced and affects the internal organs, other therapies might include:
- interferon: Some success has been found using high-dose interferon. Its use is limited to certain people, however, because it's a very toxic treatment.
- chemotherapy: As with many cancers, chemotherapy is an option in treating Kaposi's sarcoma. Because this treatment is systemic (i.e., it affects many systems in the body) or generalized, many side effects can occur. Most chemotherapy medications are given by intravenous drip (IV), but some can be taken by mouth. Some common side effects of chemotherapy include:
- nausea and vomiting
- hair loss
- shortness of breath
- mouth sores
Because Kaposi's sarcoma is likely caused by an interaction between immune suppression and exposure to the sexually transmitted infection of HHV 8, 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 AIDS. Since AIDS increases the risk of Kaposi's sarcoma, practicing safer sex can help reduce your risk of this cancer.