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Chapter 42

Kaposi Sarcoma

This chapter on Kaposi sarcoma was originally written in 1980, for the first (1981) edition. It has not been changed significantly, and is still an accurate and complete description of Kaposi sarcoma as seen in any non-AIDS patient anywhere. This does not mean that there are two separate versions of Kaposi sarcoma. There is no histological or other intrinsic difference between Kaposi sarcoma in the AIDS and in the non-AIDS patients, and there is certainly no variety peculiar to Africa alone. As described in this chapter, it was recognized long ago that Kaposi sarcoma was probably transmissible, in spite of the characteristics which suggested it was a malignant neoplasm. During the 1961 conference on Kaposi sarcoma, organized by the International Union Against Cancer, and held in Kampala, Uganda, the experts there agreed that a virus was a likely cause; the nearby Entebbe Virus Research Centre was actively searching for one, but unfortunately the available technology could not demonstrate it. Later, the evidence of a herpes-like infectious agent increased, and in 1996 the virus was more closely typed.

Kaposi sarcoma occurs in patients who are immunosuppressed for whatever reason. There is no racial or other predondnance, but there is a difference in the way the disease behaves depending on the degree of immunosuppression of the patient. One pattern is not solely a disease of old people, nor is the other found only in children or young adults; in fact Kaposi and his colleagues described an acute fulminating illness in young children, so to use the label "classical" Kaposi sarcoma has no basis. Equally, to call it a skin disease is to show complete lack of understanding of the pathology and the natural history of the disease. There are in today's literature many suggestions of apparent differences, but these are because modern technology, both in imaging and in the laboratory, allows the demonstration of aspects of the disease which could not be imaged or uncovered before. Although rare, it is important to remember that the so-called mild pattern in an elderly patient can become much more florid if the patient is subsequently immunosuppressed and that the reverse is also true, although even less common: the severity of the disease may lessen if immunosuppression is reduced.

Since 1980, when this chapter was originally written, Kaposi sarcoma has been extensively recorded and imaged in many different ways in HIV-positive patients. These are reviewed and described and the references updated in the chapter on AIDS. It is important to remember that between 1950 and 1970 many major medical centers in Africa were engaged in cancer research: very careful statistics were kept on behalf of the British Empire Cancer Campaign in centers such as Ibadan, Kampala, Nairobi, Bulawayo, and Lourenco Marques (now Maputo). All suspected cases of malignant disease were reviewed by a panel of experts who demanded a high rate of histopathology. The autopsy rate at all these hospitals was also high, not only for patients with malignant disease, but for all patients who died. Active research was going on in many different diseases and the local disease patterns were well known throughout each region. It is certain that there were no patients dying for some unknown reason with any of the symptoms which today make up the acquired immunodeficiency syndrome. The discovery in 1980 of the retrovirus now known as HIV in blood taken in the then Belgian Congo in 1959, and the deduction that the HIV clusters had developed after mutation in the late 1940s or early 1950s in the Eastern Congo, does not alter the fact that the clinical entity now recognized as AIDS did not become apparent at that time. There were, and are, many differences between diseases as seen in the tropics and nontropics. One reason is that in the tropics many patients of all ages have altered immune systems, be it from malaria, malnutrition, measles, or many other causes.

In the 1950s and 1960s, there was a free interchange of ideas between the experienced staff of all the departments in these big hospitals and universities, and many visits were made between centers by staff from all departments; pathology, surgery, radiology, medicine, and others. Between them these major centers served a very high proportion of the African population, particularly those who needed slightly more than primary care. These hospitals were major referral centers and constantly in touch with the medical staff of the small hospitals and clinics surrounding them. Many countries had excellent public health services which kept good epidemiological records. It is very difficult to believe that all the medical staff at these busy centers were all overlooking anything like AIDS, or not talking about it.

The hemangiosarcoma originally described by Kaposi in 1872 is a rare disease in Europe and North America in HIV-negative patients. Radiologists on those continents may only see one or two patients in this category during his or her career. Yet Kaposi sarcoma in non-AIDS patients is common in many parts of the tropics. In some parts of Africa it was, and still is, the commonest malignant tumor affecting young people in the HIV-negative population. Yet in this group (HIV-negative) there is an intriguing difference between the clinical picture and behavior of Kaposi sarcoma in the tropics and in other parts of the world. Without AIDS, it is almost a benign disease for older people in Europe and North America, whereas it is rapidly fatal among the younger generation in the tropics. Histologically there is no difference: the variation must be a matter of immunity, a hypothesis that is reinforced by the not infrequent association of Kaposi sarcoma with immunosuppressive therapy in patients in those parts of the world where it is otherwise uncommon. It occurs in renal and other transplant patients and in patients with ulcerative colitis on steroid maintenance, and does so with sufficient frequency to suggest that whatever causes the sarcoma is held in check in most healthy individuals by a natural immunity: yet, by all recognizable standards, it behaves as a malignant disease

Synonyms

Kaposi sarcoma. Hemangiosarcoma of Kaposi. Pigmented hemangiosarcoma. Multiple pigmented sarcoma of the skin. Idiopathic multiple hemorrhagic sarcoma. Sp: Sindrome de Kaposi. Fr: Angioreticulosarcomatose de Kaposi. Ger: Kaposi Syndrom. Idiopathisches Pigmentsarcom der Haut.

Definition

The hemangiosarcoma of Kaposi originates in the perivascular cells of Schwann. These cells are of neuroectodermal origin; thus the sarcoma is of neurovascular origin. it is related to the vascular system in the same way that neurofibromatosis is related to the nervous system. Beyond that, exact definition is impossible and there is still much controversy concerning the cells of origin.

Geographic Distribution

The hemangiosarcoma was originally described by Moricz Kohn (who changed his name to Kaposi), a physician who practiced in Vienna. He knew it as a disease of European Jewish males, for the very good reason that the majority of his patients were in that category. However, in HIV-negative patients it occurs in all races, at all ages, and in both sexes. Among non-AIDS people, it is undoubtedly more common in the indigenous inhabitants of tropical Africa than in the immigrant population. In the Democratic Republic of Congo (formerly Zaire) and the basin of the Congo River it accounts for 12% of all their malignant disease and in some parts of Africa it is seen with a frequency 200 times greater than in temperate climates. It occurs in the African (black) American, but not with increased frequency.

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Copyright: Palmer and Reeder