DEFINITION
Kaposi's sarcoma (KS) is a disease in which malignant cells form in the tissue lining the lymph vessels under the skin or in mucous membranes.
ETIOLOGY
Human herpesvirus-8 (HHV-8) is found in the lesions of all patients with KS. This virus is also called Kaposi's sarcoma herpesvirus (KSHV). Most people infected with HHV-8 do not get KS. Those infected with HHV-8 who are most likely to develop KS have immune systems weakened by disease (AIDS) or by drugs given after an organ transplant.
EPIDEMIOLOGICAL VARIETIES
There are several types of Kaposi sarcoma, including:
- Classic Kaposi's sarcoma.
- African Kaposi's sarcoma.
- Immunosuppressive treatment-related Kaposi's sarcoma.
- Epidemic Kaposi's sarcoma.
- Nonepidemic Kaposi's sarcoma.
- Classic Kaposi's sarcoma is a rare disease that gets worse slowly over many years.
Patients may have one or more red, purple, or brown skin lesions on the legs and feet, most often on the ankles or soles of the feet. Over time, lesions may form in other parts of the body, such as the stomach, intestines, or lymph nodes. The lesions usually don't cause any symptoms, but may grow in size and number over a period of 10 years or more. Pressure from the lesions may block the flow of lymph and blood in the legs and cause painful swelling. Lesions in the digestive tract may cause gastrointestinal bleeding.
Some patients with classic Kaposi's sarcoma may develop another type of cancer before the Kaposi's sarcoma lesions appear or later in life. Most often, this second cancer is non-Hodgkin lymphoma. Frequent follow-up is needed to watch for these second cancers.
- African Kaposi's sarcoma is a fairly common form of the disease found in young adult males who live near the equator in Africa. Symptoms of African Kaposi sarcoma can be the same as classic Kaposi's sarcoma. However, African Kaposi's sarcoma can also be found in a much more aggressive form that may cause sores on the skin and spread from the skin to the tissues to the bone. Another form of Kaposi's sarcoma that is common in young children in Africa does not affect the skin but spreads through the lymph nodes to vital organs, and quickly becomes fatal.
- Immunosuppressive treatment-related Kaposi's sarcoma is found in patients who have had an organ transplant (for example, a kidney, heart, or liver transplant). These patients take drugs to keep their immune systems from attacking the new organ. When the body's immune system is weakened by these drugs, diseases like Kaposi's sarcoma can develop.
Immunosuppressive treatment-related Kaposi's sarcoma often affects only the skin, but may also occur in the mucous membranes or other organs.
This type of Kaposi's sarcoma is also called transplant-related or acquired Kaposi's sarcoma.
- Epidemic Kaposi's sarcoma occurs in patients who have acquired immunodeficiency syndrome (AIDS). AIDS is caused by the human immunodeficiency virus (Hiv), which attacks and weakens the immune system. When the body's immune system is weakened by HIV, infections and cancers like Kaposi's sarcoma can develop.
Most cases of epidemic Kaposi's sarcoma in the United States have been diagnosed in homosexual or bisexual men with HIV infection.
Symptoms of epidemic Kaposi's sarcoma include lesions on different parts of the body, including any of the following:
- Skin. (1)
- Lining of the mouth.
- Lymph nodes.
- Stomach and intestines.
- Lungs and lining of the chest.
- Liver.
- Spleen.
Kaposi's sarcoma is sometimes found in the lining of the mouth during a regular dental check-up.
In most patients with epidemic Kaposi's sarcoma, the disease will spread to other parts of the body over time. Fever, weight loss, or diarrhea can occur. In the later stages of epidemic Kaposi's sarcoma, life-threatening infections are common.
The use of drug therapy called HAART (highly active antiretroviral therapy), which slow down the development of AIDS, reduces the risk of epidemic Kaposi sarcoma in HIV-infected patients.
(1)
- There is a type of nonepidemic Kaposi's sarcoma that develops in homosexual men who have no signs or symptoms of HIV infection. This type of Kaposi's sarcoma progresses slowly, with new lesions appearing every few years. The lesions are most common on the arms, legs, and genitals, but can develop anywhere on the skin.
SIGNS AND SIMPTOMS
The first sign of KS is usually the development of skin lesions. Typical lesions begin as flat or slightly raised colored spots. Sometimes they develop under the skin and do not have any unusual coloring. The lesions can develop anywhere on the body, but most often they arise on the legs, nose (especially the tip), the feet, outside parts of the ears, mouth, or genitals. In time the lesions progress to larger nodules that range in color from pink or red to blue, purple, or brown. In dark-skinned people, the lesions may be dark brown or black. Sometimes a greenish "halo" appears around the lesion. Usually the lesions are not tender or sore.
About 1 person in 3 with AIDS-related KS will develop mouth and throat lesions. These are most often on the roof of the mouth (palate) but are also found on the gums, tongue, tonsils, voice box (larynx), or windpipe (trachea). Lesions on the roof of the mouth may not cause any symptoms and may only be noticed at the dentist's office. Sometimes lesions elsewhere in the mouth or throat can cause problems which may become tender and sore, and they may bleed. KS lesions in the mouth and throat can make it hard to eat, swallow, or even breathe. Lesions in the mouth can also lead to tooth loss.
KS lesions are often present in the gastrointestinal (GI) tract when the patient is first diagnosed. This is more likely if the immune system is severely suppressed, as it is when the CD4 cell count is low. Gastrointestinal KS lesions become more common with time. Sometimes lesions can develop in the GI tract even though no lesions are found on the skin. Usually GI lesions do not cause symptoms, but they may slowly bleed. Over time, blood loss can lead to anemia (a low red blood cell count) and fatigue. In some cases GI lesions can cause abdominal pain or discomfort as well as more severe bleeding. The lesions can also make it hard to digest and absorb nutrients from food. This can lead to diarrhea and weight loss. In rare cases, the lesions can completely block the digestive tract, preventing the bowels from moving. This is called a bowel obstruction, and it may require surgery to unblock the intestine.
Some people with KS develop swelling resulting from blockage of the lymph nodes or lymph vessels. This is called lymphedema. This can occur even when there are no (or only a few) lesions visible on the skin. Most often the swelling is seen in the legs or feet, but it can also be present in the groin, the genitals, or the skin around the eyes. Only rarely does the chest or arms swell. When lymphedema in the legs is severe, the swelling can be painful or make it difficult to walk. Sometimes bacterial infections develop in areas with severe lymphedema.
When KS develops in the lungs, it can cause problems like coughing (sometimes with bloody sputum), shortness of breath, and fever.
DIAGNOSIS
Tests that examine the skin, lungs, and gastrointestinal tract are used to detect and diagnose KS.
The following tests and procedures may be used:
- Physical exam and history (an exam of the body to check general signs of health, including checking skin and lymph nodes for signs of disease, such as lumps or anything else that seems unusual. A history of the patient's health habits and past illnesses and treatments will also be taken).
- Biopsy
- Chest x-ray
- Endoscopy
- Bronchoscopy
DIFFUSION
The cancer may form metastasis spreading in the body:
- Through tissue. Cancer invades the surrounding normal tissue.
- Through the lymph system. Cancer invades the lymph system and travels through the lymph vessels to other places in the body.
- Through the blood. Cancer invades the veins and capillaries and travels through the blood to other places in the body.
PROGNOSIS
The prognosis and treatment options depend on the following:
- The type of Kaposi's sarcoma.
- The general health of the patient, especially the immune system.
- Whether the cancer has spread.
- Whether the cancer has just been diagnosed or has recurred.
Barbero Chiara e Serra Sara
