noun. a minor tumor which generally occurs in the adrenal medulla but might take place in tissues of the sympathetic paraganglia. Since it is made up of adrenal tissue, it can excrete norepinephrine and epinephrine, making extreme amounts of these catecholamines, visual blurring, tachycardia, high blood pressure accompanied by headaches, and other indicators. It is considered to be an hereditary disorder.
PHEOCHROMOCYTOMA: "There is a pheochromocytoma on the anterior portion of the brain."