[Kaposi's disease. Ultrastructural study of 4 cases].

An ultrastructural study of Kaposi's disease showed often immature vascular proliferation bordered by large globular or fusiform endothelial cells. Other cell types participated in this proliferation: inflammatory cells, pericytes and fibroblasts. These various cell types are the site of active erythrophagocytosis. It is reasonable to accept that the disease is the result of reticulo-endothelial proliferation with multiple morphological types and predominant vascular differentiation.