Aleda Nash, MD, Scott E. Woods, MD, MPH

Pheochromocytoma is a rare chromaffin cell neoplasm that secretes catecholamines and is usually found in the adrenal medulla. One fourth of these tumors are the result of genetic inheritance. Hypertension is the most common symptom. The classic triad of paroxysmal symptoms?consisting of palpitations, diaphoresis, and headaches?should prompt a consideration of this diagnosis and appropriate laboratory testing. The best biochemical marker is plasma free metanephrines, which is 99% sensitive and 89% specific for diagnosis. Magnetic resonance imaging and radioactive iodine metaiodobenzylguanidine scans are used to localize the tumor before surgery.