What Is Kaposi's Sarcoma? What Causes Kaposi's Sarcoma?

Editor's Choice
Main Category: Cancer / Oncology
Also Included In: HIV / AIDS;  Dermatology
Article Date: 08 Dec 2009 - 3:00 PDT

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Kaposi's sarcoma (KS) is a tumor caused by Human herpesvirus 8 (HHV8), also known as Kaposi's sarcoma-associated herpesvirus (KSHV). It differs from other cancers as it starts in several areas of the body at once, while other forms of cancer start in one place and then spread.

This type of tumor was first described in 1872 by the dermatologist Moritz Kaposi who died in 1902. Born in Austro-Hungary, Kaposi first identified this skin cancer in older Italian and Eastern European Jewish men.

Kaposi sarcoma is now far more common and spreads more aggressively through the body among patients with AIDS. Because of the AIDS epidemic, Kaposi sarcoma left its obscure oncologic niche and entered into daily usage during in the 1990s.

With the rise of the AIDS epidemic, KS was researched more intensively in hopes that it might reveal the cause of AIDS. The disease was erroneously referred to as the "AIDS rash". According to Medilexicon's medical dictionary:

Kaposi's Sarcomais a multifocal malignant neoplasm of primitive vasoformative tissue, occurring in the skin and sometimes in the lymph nodes or viscera, consisting of spindle cells and irregular small vascular spaces frequently infiltrated by hemosiderin-pigmented macrophages and extravasated red blood cells. Clinically manifested by cutaneous lesions consisting of reddish-purple to dark-blue macules, plaques, or nodules; seen most commonly in men older than 60 years of age and in AIDS patients, as an opportunistic disease associated with human herpes virus-8 infection.

There are four types of KS. First, KS can develop in people whose immune system has been severely weakened by HIV or AIDS. It mostly affects gay men with HIV or AIDS. KS rarely affects women or straight men with HIV or AIDS.

Second, Classic KS is a rare condition. It usually only affects men between 50 and 70 years of age who are of Mediterranean or eastern European descent. It is thought that people who develop classic KS were born with a pre-existing genetic vulnerability to the virus that causes it.

Endemic KS is common in parts of Africa and is one of the most widespread types of cancer in that region. As with classic KS, endemic KS is thought to develop due to a pre-existing genetic vulnerability to the virus that causes it.

The situation has recently been complicated by the HIV epidemic in Africa, and many people may now be more vulnerable to the virus because of a weakened immune system due to HIV or AIDS.

Finally, transplant-related KS is an uncommon complication of organ transplants. People who have had an organ transplant usually take medication to weaken their immune system to prevent their body rejecting the new organ. The weakening of their immune system makes them more vulnerable to the virus that causes KS.

What are the symptoms Kaposi's Sarcoma?

A symptom is something the patient senses and describes, while a sign is something other people, such as the doctor notice. For example, drowsiness may be a symptom while dilated pupils may be a sign.

Kaposi sarcoma is a highly vascular tumor of the skin characterized by soft purplish plaques and papules that form nodule. These typically start on the feet and ankles and then slowly spread across the skin of the legs, hands and arms. The lesions may occasionally be plaque-like even involved in skin breakdown with resulting fungating lesions. Skin lesions may be quite disfiguring for the sufferer, and a cause of much psychosocial pathology.

The mouth is involved in about 30% of cases, and is the initial site in 15% of AIDS related KS. The hard palate is most frequently affected, followed by the gums. Lesions in the mouth may be easily damaged by chewing and bleed or suffer secondary infection, and even interfere with eating or speaking.

Gastrointestinal tract involvement can be common in those with transplant related or AIDS related KS, but may occur in the absence of skin involvement. The gastrointestinal lesions may be silent or cause weight loss, pain, nausea/vomiting, diarrhea, bleeding (either vomiting blood or passing it with bowel motions), malabsorption, or intestinal obstruction.

Finally, involvement of the airway can present with shortness of breath, fever, cough, hemoptysis (coughing up blood), or chest pain, or as an incidental finding on chest x-ray. The diagnosis is usually confirmed by bronchoscopy when the lesions are directly seen, and often biopsied.

What are the causes of Kaposi's Sarcoma?

KS actually arises as a cancer of lymphatic endothelium and forms vascular channels that fill with blood cells, giving the tumor its characteristic bruise-like appearance.

HHV-8 does not cause Kaposi's sarcoma in everyone who contracts the virus. Instead, it only seems to cause Kaposi's sarcoma in people who have an inherited (genetic) vulnerability to HHV-8, or people with a weakened immune system.

Diagnosing Kaposi's Sarcoma

Although KS may be suspected from the appearance of lesions and the patient's risk factors, definite diagnosis can only be made by biopsy and microscopic examination, which will show the presence of spindle cells. Detection of the KSHV protein LANA in tumor cells confirms the diagnosis.

An endoscopy may be carried out if it is suspected that KS is in the digestive system. It allows the general practitioner to look inside parts of the digestive system, such as the bowel, liver and spleen, for any abnormalities or signs that KS is present.

What are the treatment options for Kaposi's Sarcoma?

Kaposi's sarcoma is not curable, but it can often be effectively palliated for many years, and this is the aim of treatment. An initial treatment is called HAART, or highly active antiretroviral therapy, and involves using a combination of medicines that interrupt the reproductive cycle of the HIV virus. This helps to prevent the virus from spreading quickly as well as protecting and strengthening your immune system. HIV can quickly adapt and become resistant to a single medicine, a combination of medicines is required. In a certain percentage of such patients, Kaposi's sarcoma may again grow after a number of years on HAART, especially if HIV is not completely suppressed.

As with all types of cancer, surgery, radiation therapy and immunotherapy are additional options. Often these measures are used in conjunction with HAART treatments. However, typically surgery is generally not recommended as Kaposi's sarcoma can appear in wound edges.

Preventing Kaposi's Sarcoma

There is no way to prevent the milder forms of Kaposi's sarcoma. The most effective way to avoid developing Kaposi's sarcoma is to prevent the transmission of HIV. People who are HIV-positive can decrease their risk of Kaposi's sarcoma by taking highly active antiretroviral therapy or HAART, as discussed above.

Written by Sy Kraft (B.A.)
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today

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