CLINICAL-EXPERIENCE WITH INCIDENTALLY DISCOVERED PHEOCHROMOCYTOMA

Purpose: We reviewed 17 resected pheochromocytomas comprising 7 from s ymptomatic patients, and 10 unsuspected and incidentally discovered tu mors. We compared various parameters concerning these 2 groups and inv estigated the features of the incidentally discovered pheochromocytoma . Materials and Methods: Patient gender and age, clinical symptoms and signs, tumor localization, detection methods, findings on imaging stu dies, urinary catecholamine concentrations, results of metoclopramide stimulation tests, treatments at operation and tumor size were evaluat ed. Furthermore, we compared the clinically diverse aspects arising be tween the symptomatic and incidentally discovered pheochromocytomas. R esults: The 24-hour urinary noradrenaline and vanillylmandelic acid le vels in the incidental cases tended to be lower than those in the symp tomatic cases, while 24-hour urinary dopamine was significantly less ( 468 +/- 221 compared to 1,558 +/- 899 mu g/day, respectively). Typical symptoms of pheochromocytoma were noted in 6 patients (60%) in the in cidental tumor group. The incidental cases had a markedly high false-n egative rate (71%) as noted by the metoclopramide stimulation test, al though the symptomatic cases had a 100% positive rate. On the other ha nd, the average diameter of incidental tumors was significantly larger than that of the symptomatic lesions (55.5 +/- 19.1 versus 35.9 +/- 1 2.1 mm., respectively). Conclusions: Clinical signs and findings in pa tients with incidental tumors were weaker than those with symptomatic disease although most incidental tumors functioned. Lower urinary cate cholamine values in the incidental tumors were consistent with these r esults. However, the surgical risk for incidental tumors was the same as that for symptomatic lesions. Therefore, patients with incidentally discovered pheochromocytomas scheduled to undergo surgery should be t reated accordingly.