Pheochromocytoma

Pheochromocytoma is a rare tumor of the adrenal medulla composed of chromaffin cells, also known as pheochromocytes. When a tumor composed of the same cells as a pheochromocytoma develops outside the adrenal gland, it is referred to as a paraganglioma. These neuroendocrine tumors typically release massive amounts of catecholamines, metanephrines, or methoxytyramine, which result in the most common symptoms, including hypertension (high blood pressure), tachycardia (fast heart rate), and diaphoresis (sweating). Rarely, some tumors (especially paragangliomas) may secrete little to no catecholamines, making diagnosis difficult. While tumors of the head and neck are parasympathetic, their sympathetic counterparts are predominantly located in the abdomen and pelvis, particularly concentrated at the organ of Zuckerkandl. 1920s: from phaeochrome (another term for chromaffin), from Greek phaios ‘dusky’ + khrōma ‘color’, + -cyte. The signs and symptoms of a pheochromocytoma are those related to sympathetic nervous system hyperactivity. The classic triad includes headaches (likely related to elevated blood pressure, or hypertension), tachycardia/elevated heart rate, and diaphoresis (excessive sweating, particularly at night, also known as hyperhidrosis). However, patients are unlikely to experience continuous symptoms. Due to the paroxysmal nature of catecholamine synthesis and release, patients may experience "attacks" or "spells" where they are suddenly overwhelmed with signs and symptoms of their tumor. Attacks can occur spontaneously (without warning) or may be triggered by a variety of pharmaceutical agents, foods, intraoperative tumor manipulation, intubation, or during anesthetic induction.