Comparison of Ulex europaeus I lectin binding and factor VIII-related antigen as markers of vascular endothelium in follicular carcinoma of the thyroid

Factor VIII-related antigen (F VIII-RAg), a well established marker for endothelial cells, and the lectin Ulex europaeus agglutinin I (UEA-1), a newly described marker, were used in immunoperoxidase techniques to demonstrate endothelial cells in 30 follicular neoplasms of the thyroid and so to assist in detection of vascular invasion. Both endothelial cell markers made visible a greater number of instances of vascular invasion than were detected on routine elastic stains, but UEA-1 lectin gave more reliable staining of endothelium lining large capsular veins and of blood vessels within the tumour than did F VIII-RAg. In vessels completely occluded by tumour, examples of endothelial staining by UEA-1 in the absence of F VIII-RAg staining were found, but some such vessels appeared to lack surviving endothelial cells and in these no staining occurred. It is concluded that UEA-1 lectin is a more reliable endothelial marker in this setting than F VIII-RAg and may assist the demonstration of vascular invasion in these tumours.