Intraoral Kaposi's sarcoma: a correlated light microscopic, ultrastructural, and immunohistochemical study.

Oral mucosal lesions of Kaposi's sarcoma are a common finding in patients with acquired immunodeficiency syndrome (AIDS). The histologic features of Kaposi's sarcoma vary, depending on the clinical stage of the lesion. Endothelium-lined vessels are the principal feature of early, macular lesions, while spindle cells dominate late-stage, nodular lesions. The histogenesis of both components remains controversial. In this study, biopsy specimens of intraoral Kaposi's sarcoma from 10 patients with AIDS were studied by light and electron microscopic examination and by immunoperoxidase staining with the endothelial markers, factor VIII-related antigen and Ulex europeaus agglutinin I. The results of this study support a vascular origin for both the endothelium-lined vessels and the spindle cells. The latter appear to represent vascular endothelial cells in various stages of differentiation. The histologic features that are useful in the diagnosis of intraoral Kaposi's sarcoma are reviewed.