Kaposi’s Sarcoma And Its Variants
Kaposi’s sarcoma (KS) is one of the many AIDS-defining conditions that occur in the setting of a severely compromised immune system from HIV infection, developing a blood vessel tumor that can spread throughout the body. First described by Mortiz Kaposi in the late 1800s, Kaposi’s sarcoma is an angioproliferative neoplasm (or blood vessel tumor) that can affect the skin, mucosal membrane as well as deep organs such as liver, lungs or pancreas. Kaposi’s sarcoma exists in 4 variants based on the epidemiology of each form, but what remains consistent throughout the different forms is the role of Human Herpes Virus 8 (HHV8) in the formation of this disease.
The 4 epidemiological forms of Kaposi’s sarcoma are the following:
Classic Kaposi’s Sarcoma
In 1872, Moritz Kaposi first described the condition which is now known as the classic from of KS, usually seen in elderly males of Eastern European or Mediterranean descent. The damages are usually confined to the lower extremities such as toes, ankles or shins and occur in males at a significantly higher proportion compared to females (15:1). The incidence of Kaposi’s sarcoma in the Mediterranean is also much higher compared to Europe and the United States. For instance, during the AIDS epidemic, the Italian population recorded the prevalence of the condition at 2 to 3 times higher than in the United States and up to 10 times higher than England.
AIDS-Associated Kaposi’s Sarcoma
KS in this form involves the neoplasm of the blood vessels being visible through spots on the skin that may spread to the mucosal membrane and deep organs. Along with the neoplasm (tumor), patients in this group almost always have other opportunistic infections such as Pneumocystis carinii pneumonia, caused by a fungus that is easily destroyed by a healthy immune system. When this form of KS was first discovered, 95% of all cases occurred within the homosexual male population. Compared to other epidemiological form of this condition, this variant is more aggressive and spreads to deep organs, bringing about organ failure and eventually, death. Fortunately, with the advent of antiretroviral treatment (HIV treatment), the incidence of this form of Kaposi’s sarcoma has dropped significantly – from its peak of 33.3 cases per 100,000 people at the height of the AIDS epidemic in 1991, to just 2.8 cases per 100,000 people in 1998, after antiretroviral treatment was made widely available.
Endemic Kaposi’s Sarcoma
In the 1950s, an endemic (local) form of Kaposi’s Sarcoma was identified in Africa and it became one of the most common neoplasms (cancers) observed in Central Africa, affecting men, women and children. After the AIDS epidemic, the incidence of KS within the region increased drastically, with Kaposi’s sarcoma making up 48.6% of all cases of cancer within the male cancer patient population and the prevalence of KS in women increased to 17.9%.
Iatrogenic Kaposi’s Sarcoma
In the 70’s, iatrogenic KS was observed among organ transplant recipients, as well as other patients on long-term immunosuppression for other diseases. When the immune system is suppressed through therapy, the body becomes increasingly vulnerable to HHV8 infection and KS can develop. In fact, the incidence of KS is 400 – 500 times higher among such patients than the general population.
Recently, a growing number of iatrogenic KS cases has been reported amongst patients who are undergoing long term-corticosteroid therapy or biologic therapy such as rituximab and infliximab. However, KS in such patients frequently resolves spontaneously when the immunosuppressive therapies are discontinued.
If you are concerned that you are at risk of developing KS, please consult your doctor to learn the necessary steps to protect yourself.
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