PHEOCHROMOCYTOMA - A tumor of the adrenal gland which produces catecholamines (norepinephrine and epinephrine). Although the tumor is usually benign it produces hypertension, pounding headaches, tachycardia, palpitations, apprehension, facial flushing, nausea, and vomiting. A diagnosis can be made using a urine test which measures the quantity of epinephrine byproducts. Adrenal tumors may be detected using CT scanning, MRI scanning, or a nuclear scan of the adrenal glands.