Kaposi’s sarcoma

1 - ACKNOWLEDGEMENTS

Chapter written with the help of the EADV, the Fondation René Touraine and the Therapeutics in Dermatology

2 - OVERVIEW

Kaposi sarcoma (KS) is a type of cancer that mostly grows on the skin, but can also form masses in oral mucosa, lymph nodes, and visceral organs. It was described by a dermatologist from Vienna in the nineteenth century and acquired notoriety in the 1980s, when associated with HIV infection, constituting a stigma that segregated these patients.

Most patients present with cutaneous disease, but visceral disease may occasionally precede cutaneous manifestations. Human herpesvirus 8 (HHV8) is found in the lesions of all patients. Risk factors include poor immune function, either as a result of disease or specific medications, and chronic lymphedema.

KS can be categorized into four types. One is called Classic, a rare form mainly observed in Jewish and Mediterranean populations. It happens mostly in older adults, affects the legs and tends to be slow growing, not always needing to be treated. Its occurrence may be due to immune suppression from age, host genetics, history of other neoplasia, and possible concurrent infections such as malaria.

Another type is called Epidemic and occurs in people who have AIDS, being the most common form. As immune system of these patients cannot fight off infections or cancer well, the tumor usually grows quickly and needs to be treated. It is the most clinically aggressive form of KS, especially where access to antiretroviral therapy is limited.

The immunosuppression therapy-related type generally happens in people who have had organ transplant surgery and mostly affects the skin. In some patients, the withdrawal of immunosuppression may cause regression of the disease.

Endemic type occurs in individuals of sub-Saharan African regions and it is unusually aggressive. This can be divided into 2 subtypes: the lymphadenopathic, a very aggressive form that affects very young children, and the cutaneous form that affects young and middle-aged adults.

3 - SIGNS AND SYMPTOMS

People with KS do not always present signs or symptoms of the cancer. However, in many people, cutaneous lesions suggest the disease.

It often presents as marks on the skin as red, pink, purple, or brown blemishes called macules. It usually starts out flat, but can become raised or bumpy, with a blue-violet to black tonality. It often appears on the legs or feet, but can grow on the nose or genitals, occasionally associated with swelling and outward or inward growth into the soft tissue or bone.

Although this tumor is typically found on the skin, spread elsewhere is common, especially to the mouth in people with HIV or AIDS, gastrointestinal tract and respiratory tract.

4 - WHO GETS AND CAUSES

All forms of KS are caused by HHV8. Most people with this virus do not develop KS unless their immune system is suppressed.

HHV8 seroprevalence varies between different geographic regions and sub-populations. Until the advent of the HIV/AIDS epidemic, KS had occurred mainly in older men of Mediterranean and Jewish origin (classic KS) or in equatorial Africa as an endemic form. Outside HHV8 endemic regions, high HHV8 antibody prevalence has been described in men who have sex with men and in migrants from African regions.

HHV8 has several modes of transmission – it can be spread both sexually and non-sexually, including through organ transplantation and breastfeeding.

As HHV8 can be transmitted through saliva, infection appears to be more easily spread through certain types of sexual activity, including oral-anal contact, oral-genital contact, and deep kissing. Given this, the infection is much higher in men who have sex with men when compared to the general population.

People with weaker immune systems are at risk of KS, including individuals who are taking medication to suppress the immune system after an organ transplant and seniors whose immunity has declined. Besides this, the infection is much more common in Africa, due to the higher risk of malaria, other chronic infections and malnutrition, that compromise immunity. Rarely or never wearing shoes is associated with this tumor in rural areas with volcanic clay soils, possibly related to chronic lymphatic obstruction in the feet and legs from fine soil particles. So, other risk factors for HHV8 infection, include lack of circumcision, rural residency, lower socioeconomic status, and malaria parasitaemia.

5 - DIAGNOSIS AND TREATMENT

Although the diagnosis may be suspected from the appearance of lesions and the patient’s risk factors, definite diagnosis can be made only by tissue biopsy and microscopic examination. The extent of the extracutaneous disease may be determined by medical imaging.

KS is not curable, but it can often be treatable for many years. Treatment is based on the sub-type, the speed of growth, whether the disease is localized or widespread, and the patient’s immune function. In tumors associated with immunodeficiency or immunosuppression, treating the cause of the immune system dysfunction can slow or stop the progression of the disease. When associated to AIDS, the lesions are typically not treated directly, as they will shrink upon first starting antiretroviral therapy. These medicines help to keep the HIV virus under control, so that the immune system can work better and also combat KS.

People with few local lesions may be treated by surgery (to remove the cancer), injections of chemotherapy in the site or radiation therapy, to kill the cancer cells. More widespread disease or affecting internal organs is treated with chemotherapy or immunomodulatory therapy, to kill cancer cells or stop them from growing.

6 - TIPS FOR MANAGING

Since HIV can be spread through sex and many people with HIV do not know that they are infected, it is recommended to use a condom during any sexual contact. It is also important to avoid deep kissing with partners with HHV8 infection or whose status is unknown.

HIV can also be spread through the use of contaminated needles to inject recreational drugs and the safest way to avoid infection is to quit. If not possible, clean needles and injection supplies can help to protect.

HIV-infected mothers can pass the virus to their babies during pregnancy, delivery, or breastfeeding. Treating the mothers and infants with anti-HIV drugs and avoiding breastfeeding can greatly reduce this risk.

As HHV8 is also transmissible via organ transplantation and blood transfusion, testing for the virus before these procedures limits iatrogenic transmission, a much more controlled route currently.

Therefore, to conclude, the main prevention is based on correct behaviors and attitudes of the population.