Heparanase-1 and Cyclooxygenase-2: prognostic indicators of malignancy in pheochromocytomas

The objective of this article is to evaluate Heparanase-1 and Cyclooxygenase-2 as tissue-based markers of pheochromocytoma prognosis. Ninety-two sporadic pheochromocytoma patients with a minimum of 8-year follow-up post-diagnosis were enrolled. Slides of normal adrenal glands in nephrectomy specimens from 20 patients with benign renal tumors were as control. Heparanase-1 and Cyclooxygenase-2 expression as well as microvessel density were examined using immunohistochemistry in tissues from these patients. Positive staining for Heparanase-1 was observed in 23.68% of the benign and 77.78% of the malignant cases, whereas none of the normal adrenal controls showed positive staining. Similarly, Cyclooxygenase-2 staining was seen in 23.68% of the benign versus 83.33% of the malignant cases, and none of the normal controls appeared positive for Cyclooxygenase-2. Using both HPA-1 and Cox-2 combined, the positive predictive value of malignancy was significantly increased to 0.72, compared to about 0.45 by their own. Malignant cases showed higher microvessel density compared to benign tumors and normal controls (36.41, 21.43, and 13.36%, respectively). Heparanase-1 and Cyclooxygenase-2 may contribute to the invasive characteristics of malignant pheochromocytomas. Heparanase-1 and Cyclooxygenase-2 combined is better than their own to be used as a marker to distinguish malignant from benign pheochromocytoma.