Kaposi sarcoma or KS is a type of tumor that is cancerous in nature, but differs from other types of cancer in terms of the underlying cause. It begins as a cancer of the cells lining the vessels of the blood or lymphatic circulatory systems.

Channels form within the vessels and fill with blood cells. These channels are irregular and blood cells leak from them, leading to the characteristic appearance of the tumors.

What causes Kaposi sarcoma?

The sarcomas usually appear on the skin as lesions that are red, purple, black or brown in color. The lesions are raised and may at first look something like large moles. Depending on the area of the skin affected, the lesions may initially appear plaque-like. They can cause skin breakdown and lead to ulcerations or necrosis. The surrounding skin may swell and be painful.

The lesions may also be found in the mouth. In some cases, they grow in the gastrointestinal or respiratory tract where they cause other symptoms. When located in the mouth, the lesions may bleed and interfere with speak or chewing. Secondary infections are common when they are present in the mouth.

In the GI tract, Kaposi sarcoma can cause weight loss, pain, vomiting, diarrhea and bleeding. They can also interfere with nutrient absorption and sometimes cause intestinal blockages.

If present in the respiratory tract, KS can cause coughing, shortness of breath, chest pain, fever or coughing up blood.

The cause of KS is a virus called human herpes-virus 8 or HHV8. Although the appearance is most often associated with the AIDS virus, it is actually an opportunistic infection. People with HIV are more likely to become infected with HHV8, because their body’s immune systems are already weak. The virus was discovered in 1994 and has since been shown to be present in every tumor examined.

What are the KS treatment options?

Treatment for Kaposi sarcoma varies depending on the severity and on whether or not the patient is HIV positive. In AIDS-associated KS, Highly Active Antiretroviral Therapy or HAART is usually the first line of treatment. In most cases, the tumors shrink after starting HAART.

When the tumors are small and present only on the skin, cryosurgery or radiation therapy can sometimes be used to shrink or destroy the lesion. Other types of surgery are not usually recommended, as the sarcomas can appear in the edges of the wound left after surgery. Stronger cancer treatments such as interferon alpha are used when the internal organs have been affected or there is wide spread disease.

Kaposi sarcoma is most common in AIDS patients and in transplant recipients, but is can occur in non-HIV infected people. Screening for the HHV8 virus has been recommended, but currently there is no system in place to screen organs or patients.