Kaposi's sarcoma in Zambia. A histopathological study

Fifty nine cases of Kaposi's sarcoma were studied. This sarcoma constitutes 2.7% of all histologically proven malignant tumors seen during the 3 yr period of study. Most patients were between 20 and 55 yr of age (whites usually over the age of 50). The male:female ratio was 6.3. The low prevalence sex ratio in children (3.5) is in agreement with the figure of 3.7 in Ugandan and 3.2 in East African children. The reason for the increase in incidence after puberty is not understood. An environmental influence is unlikely because this higher adult prevalence has also been observed in both African and American patients. Estrogenic hormones might have some protective effect in later life, but the disease occurs during pregnancy and is unaffected by the oral administration of estrogen. It has been suggested that some genetic factor, possibly located on the X chromosome, may protect the females. The hemorrhagic and granulomatous lesions described by Dorffel (1932) are seldom seen in Zambians. The incidence of the different histologic types seen in different geographical areas is shown in a table. The mixed cell pattern was the most frequent subtype in Zambia (78%), which was also noted in Uganda, while the monocellular and anaplastic patterns were less common. The varied histologic pattern may be related to the immune status with the more malignant monocellular and anaplastic variants resulting from a more severe impairment of the immune mechanism. The Taylor et al. (1971) classification was found to be useful in the present study. The occurrence of associated cancers and leukemias, the histogenesis and the differential diagnosis are discussed.