Endemic and atypical Kaposi's sarcoma in Africa--histopathological aspects.

Atypical HIV-associated and endemic Kaposi's sarcoma (KS) differ in their clinical presentation and behaviour. To assess the possible histological differences, a detailed review of 32 cases of atypical KS and 170 cases of endemic KS from sub-Saharan Africa was undertaken. Both forms of KS had similar histological appearances, and evolved through a chronological sequence of patch, plaque and nodule. There was an increase in the proportion of early patch and plaque lesions in cutaneous and mucosal atypical KS (54%) compared with endemic KS (23%). However, nodular lesions were still seen in atypical KS, and formed 56% of the total cases. In addition, atypical KS tended to have more small blood vessels and a lesser degree of inflammatory infiltrate. However, within each of the three stages of the disease, it was not possible to distinguish between the HIV- and non-HIV-related forms.