APA Dictionary of Psychology

n. a small tumor that usually develops in the adrenal medulla but may occur in tissues of the sympathetic paraganglia. Because it is composed of adrenal tissue, it can secrete epinephrine and norepinephrine, producing excessive levels of these catecholamines. Effects include hypertension with headaches, tachycardia, visual blurring, and other symptoms. It is believed to be an inherited disorder.