DIFFERENT IMMUNOREACTIVITY OF ENDOTHELIAL MARKERS IN WELL AND POORLY DIFFERENTIATED AREAS OF ANGIOSARCOMAS

This study evaluated the immunohistochemical staining of four endothel ial cell markers in well differentiated and poorly differentiated area s of angiosarcomas. Formaldehyde-fixed, paraffin-embedded sections fro m eight angiosarcomas were studied using the antibodies anti-factor VI II-related antigen (FVIII-RA), Ulex europaeus I agglutinin, anti-CD34 (QBEND/10) and anti-CD31 (JC70). The immunostaining of the angiomatous (well differentiated) and solid (poorly differentiated) areas was sep arately analysed and specificity was evaluated in 20 non-vascular tumo urs. The antibody anti-CD31 and Ulex europaeus were the most sensitive markers staining well differentiated vasoformative structures and poo rly differentiated solid areas. Anti-FVIII-RA and anti-CD34 did not st ain undifferentiated malignant endothelial cells from solid areas. Ule x europaeus and anti-CD34 showed very low specificity; in contrast, no ne of the non-vascular tumours expressed CD31 or FVIII-RA. JC70 (anti- CD31) appears to be the most useful marker in elucidating the vascular nature of angiosarcomas. Is important to emphasize the lack of specif icity of Ulex europaeus and the low sensitivity of anti-CD34 and anti- FVIII-RA for poorly differentiated lesions.