Pheochromocytomas: Can malignant potential be predicted?

Objectives. The presence of metastatic lesions is the only acceptable fact to confirm malignant pheochromocytoma. Patients with malignant pheochromocy tomas, however, have a very poor survival rate. The aim of our study was to postulate predictive values for malignant pheochromocytomas. Methods. We evaluated symptoms, diagnostic modalities, treatment, and long- term follow-up of 86 patients with 85 benign and 10 malignant pheochromocyt omas. Parameters from the benign were compared with those of the malignant pheochromocytomas. Results. Preoperative 24-hour urinary dopamine was in the normal range for benign pheochromocytomas but increased in malignant pheochromocytomas (P <0 .0001). Vanillylmandelic acid was elevated in both benign and malignant phe ochromocytomas but higher in malignant than in benign tumors (P = 0.01). No differences could be shown in urinary epinephrine and norepinephrine sampl ings. Tumor location was divided into 77 adrenal (81%) and 18 extra-adrenal (19%) sites. Malignant pheochromocytomas were located more often at extra- adrenal sites (P = 0.03). There was no increased incidence of malignancy in patients with familial bilateral pheochromocytomas or multiple endocrine n eoplasia. Tumors greater than 80 g in weight corresponded to malignancy (P <0.0001). Dopamine tumor concentration was higher in malignant than in beni gn pheochromocytomas (P = 0.01). Persistent arterial hypertension occurred in 9 (13%) of 72 benign and 6 (60%) of 10 malignant pheochromocytomas (P = 0.001). The 10-year survival rate was 94% for benign pheochromocytomas. All patients with malignant pheochromocytomas died within this period (P = 0.0 001), Conclusions. High preoperative 24-hour urinary dopamine levels, extra-adren al tumor location, high tumor weight, elevated tumor dopamine concentration , and postoperative persistent arterial hypertension are all factors that i ncrease the likelihood of malignant pheochromocytoma. Patients with these c haracteristics should have more frequent follow-up evaluations to identify malignancy at earlier states. (C) 1999, Elsevier Science Inc. All rights re served.