TUMOR ANGIOGENESIS IN PHEOCHROMOCYTOMAS AND PARAGANGLIOMAS

Background. Angiogenesis correlates with growth and likely metastases in several tumors. To determine whether it has a similar role in pheoc hromocytomas immunohistochemical staining of factor VIII was done on t he tumor tissue of 42 patients. Methods. Formalin-fixed, paraffin-embe dded tissue was obtained from 29 women and 13 men with 24 primary adre nal and 18 extraadrenal pheochromocytomas. Patients were divided into two groups. Group I included 32 patients with benign pheochromocytomas , and group 2 included 10 patients with malignant tumors evidenced by capsular or vascular invasion (six), liver metastases (three), or peri aortic lymph node metastates (one). Blood vessels highlighted by facto r VII staining of endothelial cells with labeled streptavidin-biotin w ere counted under light microscopy, Mean vessel count within a 10 mm(2 ) micrometer disk was calculated under x100, x200, and x400 magnificat ion fields. Results. There were no significant differences in patient age or clinical symptoms between the groups. The mean tumor size in gr oup 2 of 8.8 +/- 5.3 nn was larger than the mean of 4.8 +/- 2.8 nn in group 1 (p < 0.005). The mean counts of vessels in the x100, x200, and x400 magnification fields were 102 +/- 48, 40 +/- 18, and 19 +/- 9 in group 1, and 203 +/- 77, 73 +/- 28, and 37 +/- 15 in group 2. The num ber of blood vessels in group 2 was significantly higher than in group 1 (p < 0.001) in each studied field. Conclusions. In this study the n umber of tumor blood vessels correlated with the invasive behavior of pheochromocytomas. Tumor angiogenesis may be useful in determining the likelihood of malignant behavior in pheochromocytomas.