Multicentric angiosarcoma (Kaposi's sarcoma). Light and electron microscopic and immunohistological findings of idiopathic cases in Europe and Africa and of cases associated with AIDS.

Comparison of idiopathic Kaposi's sarcoma in Europe and Africa and Kaposi's sarcoma in connection with AIDS shows an identical morphological appearance in all three types. Ultrastructural and immunohistological investigations indicate that the tumour originates from the endothelial cells of proliferating capillaries and is therefore a vascular tumour. The clinical course and the sites of manifestation differ slightly in idiopathic cases and those occurring in connection with AIDS. This effect may be determined by the general condition of the patient, the state of immune deficiency and the influence of opportunistic infections.