Clinically Silent Pheochromocytoma in Adrenal Incidentaloma:A Case Report and Review of the Literature

Improvements in imaging studies have resulted in an increase in incidentally discovered adrenal tumors. The adrenal incidentaloma was found in at least 2% on abdominal CT imaging, and pheochromocytoma was reported to be about 5.1 to 6.5% among these patients. Here we report a case of silent pheochromocytoma presented as an incidentally discovered adrenal mass on abdominal sonogram. Clinically no apparent symptom and sign of pheochromocytoma was noted. Urine normetanephrine was 1072.2μg/day, 2.4 fold above the upper reference limits, metanephrine and 3-methoxytyramine were still within normal range. Surgical excision of the tumor in the right adrenal gland was performed with pathological report as a benign pheochromocytoma. Although transient hypertension was noted during the procedure of laparoscopic adrenalectomy, there was no complication occurred through the course. Majority of incidentally discovered adrenal masses are nonhypersecretory benign adenomas; but a hormone screening evaluation is necessary to reveal cases with clinically unsuspected hypersecretory nature. For prevention of possible lethal outcome, patients with silent pheochromocytoma scheduled to undergo surgery should be treated according to the hemodynamic parameters. ( J Intern Med Taiwan 2003;14:248-254 )