Kaposi sarcoma

Kaposi sarcoma (KS) is a cancer of the blood vessels or lymph system and is known for producing reddish or purple plaques on the skin. The most common form of Kaposi sarcoma is associated with infection by the human immunodeficiency virus (HIV), the virus that causes AIDS. The AIDS-related version of Kaposi sarcoma may be aggressive if it isn’t treated. It may form sores on the skin, spread to the lymph nodes, and sometimes involve the gastrointestinal tract, lungs, heart and other organs.

• About one in 200 transplant recipients in the United States develops KS.
• Human herpesvirus-8 (HHV-8), also called Kaposi sarcoma-associated herpesvirus (KSHV), is present in the lesions of every person affected by Kaposi sarcoma. It’s most common in areas with high HHV-8 infection rates.
• Most people with HHV-8 don’t develop KS. However, people with HHV-8 whose immune systems are compromised by a disease such as HIV or by drugs taken after an organ transplant are more likely to develop KS.

Types of Kaposi sarcoma

Below are the four main types of Kaposi sarcoma.

Epidemic (AIDS-associated) Kaposi sarcoma: The most common form in the United States, epidemic or AIDS-associated KS develops in people with HIV.

Classic (Mediterranean) Kaposi sarcoma: This form of KS mainly affects older people of Mediterranean, Middle Eastern and Eastern European ethnicities or Ashkenazi Jewish ancestry. It’s more common among men than women, and typically manifests in the form of one or more lesions on the legs, ankles or soles of the feet.

Endemic (African) Kaposi sarcoma: Endemic KS, or African KS, affects people who live in equatorial Africa. The risk of developing KS is higher in these populations, because KSHV infection is far more common in Africa.

Iatrogenic (transplant-related) Kaposi sarcoma: This is the type of KS that affects people whose immune systems are compromised due to an organ transplant.

Symptoms of Kaposi sarcoma

Signs and symptoms may vary depending on the type of KS and individual circumstances. Signs of classic KS often include slow-growing red or purple lesions on the legs and feet. Additional lesions may appear in other areas of the body, such as the lymph nodes, stomach and intestines. These lesions may interfere with the flow of blood and lymph in the legs and lead to swelling and pain. Additionally, lesions that form in the digestive tract may lead to gastrointestinal bleeding.

A sign of epidemic KS is the formation of lesions in multiple parts of the body, including:

• Skin
• Lining of the mouth
• Lymph nodes
• Stomach
• Intestines
• Lungs
• Lining of the chest
• Liver
• Spleen

Dentists sometimes discover Kaposi sarcoma in the lining of the mouth during regular dental checkups.

Who is at risk?

At-risk populations for KS include:

• People with HIV
• People who’ve had an organ transplant
• Adults and children living in equatorial Africa
• Older men of Mediterranean, Middle Eastern or Eastern European origin, or has Ashkenazi Jewish ancestry

In the United States, KS cases have decreased overall through the years. But certain populations and regions tend to be hit harder with the disease. African-Americans tend to be disproportionately affected.

How is Kaposi sarcoma diagnosed?

Kaposi sarcoma is diagnosed through a physical examination of the skin, lungs and gastrointestinal tract. Doctors may:

• Ask questions about the patient’s health history
• Examine the lungs through an X-ray
• Perform a biopsy to remove:
  • The whole lesion with a scalpel (excisional biopsy)
  • Part of the lesion with a scalpel (incisional biopsy)
  • Part of the lesion with a wide needle (core biopsy)
  • Part of the lesion with a thin needle (fine-needle aspiration biopsy)

In addition, an endoscopy or bronchoscopy may be performed to look for KS lesions in the lungs or gastrointestinal tract.

After a diagnosis of Kaposi sarcoma, additional tests are performed to see whether cancer cells have spread to other areas of the body. These may include:

• Blood chemistry studies, which involve taking a blood sample to measure the quantity of certain substances in the blood
• Computed tomography (CT) scan, which consists of detailed pictures of certain internal areas of the body, including the liver, lung and spleen.
• Positron emission tomography (PET) scan, which is a procedure performed to locate cancerous lesions in the body. It involves injecting a small quantity of radioactive glucose into a vein.
• CD34 lymphocyte count, which is a procedure where a blood sample is assessed to measure the number of CD34 white blood cells.

How is Kaposi sarcoma treated?

Treatment depends on the type of KS, general health (particularly as pertains to the immune system), and whether the cancer was recently diagnosed or recurrent. Currently, there are six standard treatments for KS. They include:

• Highly active antiretroviral therapy (HAART), which combines several drugs to reduce immune system damage caused by HIV infection.
• Radiation therapy, which involves the use of high-energy X-rays or other forms of radiation to destroy cancer cells or prevent them from growing.
• Cryosurgery (also called cryotherapy), which involves freezing and destroying abnormal tissue.
• Surgery, which may involve any of the following procedures:
  • Local excision, to remove cancer from the skin, along with a small quantity of normal tissue surrounding it.
  • Electrodesiccation and curettage, in which the tumor is removed with a spoon-shaped instrument called a curette, then a needle-shaped electrode is applied to treat the affected area with electric current.
• Chemotherapy, involving the use of drugs to stop cancer cells from growing, either by preventing cells from dividing or by destroying them.
• Immunotherapy, using the immune system to fight cancer through substances that naturally occur in the body or that are produced in a lab to help the body’s natural defense mechanisms.

There are also new KS treatments called targeted therapies, such as monoclonal antibody therapy and tyrosine kinase inhibitors (TKIs). These are being tested in clinical trials.