Angiosarcomas arising in edematous extremities: immunostaining for factor VIII-related antigen and ultrastructural features.

Immunostaining for Factor VIII-related antigen was seen in deparaffinized sections from 19 of 20 postmastectomy angiosarcomas and from four of four sarcomas that arose in chronically edematous tissue unrelated to breast carcinoma. Staining was also seen in sections from two malignant hemangioendotheliomas, four capillary hemangiomas, and one granulation tissue specimen. Sections from two lymphangiomas were immunonegative for Factor VIII-related antigen in the endothelium of lymphatic channels, whereas staining was observed in the surrounding normal blood vessels. Electron microscopic study of four postmastectomy angiosarcomas disclosed ultrastructural features (fenestrae, intense pinocytotic activity, cell junctions, and Weibel-Palade bodies) supporting the blood vascular endothelial nature of the neoplastic cells. It is concluded that a neoplastic blood vessel component is present in sarcomas that arise in chronically edematous tissues. It is questionable whether a lymphatic component is also present. These tumors, therefore, should be regarded as angiosarcomas rather than lymphangiosarcomas.