The epidemiology of classic, African, and immunosuppressed Kaposi's sarcoma.

The etiology of Kaposi's sarcoma remains somewhat obscure. While lesions of classic Kaposi's sarcoma, African Kaposi's sarcoma, and immunosuppressed Kaposi's sarcoma have been found to be indistinguishable from one another, the reasons for the variations in type and severity have not been established. The origin of the spindle cell is yet to be agreed on. Geographic variation does not seem as important as ethnic variation. The very young and the very old, perhaps two ages of weakened immunity, tend to have a higher incidence of Kaposi's sarcoma. Children and AIDS patients tend to develop more virulent disease. Males tend to get Kaposi's sarcoma at higher rates than do females. Jewish and Mediterranean males have the highest incidence of classic Kaposi's sarcoma, and African Bantu have the highest incidence of African Kaposi's sarcoma, classifications which do not apply to the Kaposi's sarcoma population in the United States. Male homosexuals have much higher incidence of Kaposi's sarcoma than do male heterosexuals, but since the early 1980s, its incidence as the presenting manifestation of AIDS has decreased dramatically. There is no unequivocal association with HLA haplotype (though DR5 carriers may be at especially high risk) or evidence of family clustering. There is an impressive but not always consistent association between Kaposi's sarcoma development and immunodeficiency. Environmental factors, such as nitrite use, immunosuppression, and repeated cytomegalovirus infection, are associated with Kaposi's sarcoma, but the exact mechanism is unclear and the associations remain inconsistent. Finally, it is still unclear if there is a causative infectious agent for Kaposi's sarcoma. While cytomegalovirus has been linked to Kaposi's sarcoma, there are weaknesses in its hypothetical role as an etiologic agent as is the case for HIV itself.(ABSTRACT TRUNCATED AT 400 WORDS)