Ocular adnexal Kaposi's sarcoma in acquired immunodeficiency syndrome. We examined histopathologically 18 ocular adnexal Kaposi's sarcoma lesions related to acquired immunodeficiency syndrome. These lesions were classified into three types. Type I consisted of thin, dilated vascular channels lined by flat endothelial cells with lumen-containing erythrocytes. Type II featured plump, fusiform, endothelial cells, often with a hyperchromatic nucleus and foci of immature spindle cells and occasional slit vessels. Type III was characterized by large aggregates of densely packed spindle cells with hyperchromatic nuclei, occasional mitotic figures, and abundant slit spaces often containing erythrocytes in between. Clinically, type I and type II tumors were patchy and flat (less than 3 mm in height) and of less than four months' duration. Type III tumors were nodular and elevated (greater than 3 mm in height). We describe the clinical and histopathologic types of Kaposi's sarcoma that may help in diagnosis. 