Kaposi's sarcoma is an uncommon type of cancer that has been rare for decades but has been seen in medical practice quite often after the onset of the AIDS pandemic and the increased incidence of treatments involving immunosuppressive drugs, as is the case of organ transplants.
Kaposi's sarcoma is an indolent cancer that arises from the tissues of blood and lymph vessels. Cancer cells from Kaposi's sarcoma form tumors that usually appear as purplish or brownish nodules on the skin.
Kaposi's sarcoma is caused by a virus subtype of the Herpesvirus family, called HHV 8 or KSHV (Kaposi sarcoma herpes virus). Although they are from the same family, HHV 8, which causes Kaposi's sarcoma, has nothing to do with HHV 1 and HHV 2, which cause cold sores and genital herpes.
Although the HHV 8 virus is responsible for the onset of this tumor, only its infection is not sufficient for the development of the disease. In fact, only 0.03% of healthy people infected with HHV 8 develop Kaposi's sarcoma. This very low rate of illness is due to the fact that our immune system is able to control the virus, which meant that for centuries Kaposi's sarcoma was a very rare tumor.
However, since the emergence of the AIDS pandemic in the 1980s and the development of treatments that involve immunosuppressive drugs, as in the case of organ transplantation and autoimmune diseases, the number of people living with their compromised immune system has progressively increased, bringing with it a range of new diseases that were once rare, including Kaposi's sarcoma. Among the immunosuppressive drugs most associated with the onset of Kaposi are Cyclosporine and corticosteroids.
It is not well known how the transmission of HHV 8 from one person to another is made, but it seems that the sexual route and the transmission through the saliva are the main routes.
In this text we will emphasize Kaposi's sarcoma related to HIV infection, but it is worth spending a few lines talking about classic Kaposi's sarcoma, which appears in healthy patients with intact immune system.
Classic Kaposi's sarcoma
Classic Kaposi's sarcoma is a rare, indolent, non-immunosuppressive tumor that occurs more frequently in elderly people ethnically related to the people of the Mediterranean and the Middle East.
There is also a second form called African Kaposi's sarcoma, also rare and unrelated to immunosuppression, occurring in people in equatorial Africa. This form differs from classical Kaposi because it is more aggressive and affects young people and children.
Kaposi's sarcoma related to AIDS
Despite being a type of cancer known since the 19th century, Kaposi's sarcoma became relatively common only from the 1980s, with the outbreak of AIDS.
Kaposi is a tumor typically of men, being 15x more common than in women. It is not known why, but the disease affects mainly homosexual men, being less common in seropositive men who acquired HIV through blood transfusion, injecting drugs or by sex with women.
Unlike the classical form, Kaposi's sarcoma in AIDS can be a widespread and rapidly evolving disease, causing significant mortality. Currently, however, because of the high efficacy of antiretrovirals in HIV control, Kaposi is not usually as aggressive as we saw in the 1980s and 1990s.
The involvement of the skin is the most characteristic and common symptom, mainly affecting lower limbs, face, oral mucosa and genitalia. The lesions vary between spots and small nodules of rounded shape. Colors can range from purple, red and brown. The lesions are usually asymptomatic, do not ache and do not cause itching.
In addition to the typical skin lesions, Kaposi's sarcoma is also very common in the oral mucosa, affecting about 30% of patients. The palate (the roof of the mouth) and the gum are the most affected places.
In patients with severe immunosuppression, Kaposi's sarcoma may develop in internal organs, the respiratory tract and gastrointestinal tract being the most common. In these cases, the symptoms are similar to any other tumor in these sites, such as shortness of breath, cough with or without blood in the sputum, chest pain, stool bleeding, intestinal obstruction and diarrhea.
The tumor can arise in any organ of the body, including lymph nodes, bones, pancreas, testicles, liver, heart and muscles.
The diagnosis of Kaposi is usually simple, being obtained through a skin biopsy. After establishing the diagnosis, the next step is to evaluate the stage of the disease, defining whether it is restricted to the skin, or has already affected internal organs. The higher the degree of immunosuppression, and in HIV this is defined by the CD4 + count and viral load, the greater the risk of diffuse disease. Confirmation of Kaposi's sarcoma is one of the criteria for classifying a HIV positive and AIDS carrier.
In classical Kaposi's sarcoma the treatment includes chemotherapy and radiotherapy according to the stage and location of the tumor.
In Kaposi's sarcoma related to AIDS or immunosuppression, the main goal is to try to restore the immune system. In the AIDS patients, the beginning of the anti-retroviral cocktail is indicated. In patients receiving immunosuppressants, these drugs should be discontinued, or at least reduced doses to try to reduce the degree of immunosuppression. If the disease is extensive, chemotherapy may be indicated.
