PECAM1 and neoplasm: CD31 and CD34 immunostaining revealed increased microvessel density in both the high and average vessel density regions of mucinous (222.4 +/- 24.8; 79.9 +/- 8.5) compared with serous (105.4 +/- 20.7; 33.3 +/- 6.8) and benign (84.4 +/- 19.4; 20.4 +/- 4.4) tumours (P < 0.001).