phaeochromocytoma

Pheochromocytoma (British English: phaeochromocytoma) is a rare tumor of the adrenal medulla composed of chromaffin cells and is a pharmacologically volatile, potentially lethal catecholamine-containing tumor of chromaffin tissue. It is part of the paraganglioma (PGL). These neuroendocrine tumors can be sympathetic, where they release catecholamines into the bloodstream which cause the most common symptoms, including hypertension (high blood pressure), tachycardia (fast heart rate), sweating, and headaches. Some PGLs may secrete little to no catecholamines, or only secrete paroxysmally (episodically), and other than secretions, PGLs can still become clinically relevant through other secretions or mass effect (most common with head and neck PGL). PGLs of the head and neck are typically parasympathetic and their sympathetic counterparts are predominantly located in the abdomen and pelvis, particularly concentrated at the organ of Zuckerkandl at the bifurcation of the aorta.

== Signs and symptoms == The symptoms of a sympathetic pheochromocytoma are related to sympathetic nervous system hyperactivity. The classic triad includes headaches (likely related to elevated blood pressure, or hypertension), tachycardia/elevated heart rate, and hyperhidrosis (excessive sweating, particularly at night). 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 (including histamine, metoclopramide, glucagon, and adrenocorticotropic hormone), foods that contain tyramine (cheese and wine), intraoperative tumor manipulation, intubation, or during anesthetic induction. thumb|alt=|250x250px|Adrenal gland; the Adrenal medulla|medulla (center, red) is the origin of the pheochromocytoma. thumb|There is an adrenal gland, highlighted in yellow, on top of each of the kidneys. Other clinical manifestations that have been reported include (in no particular order): Pallor Heat intolerance Weight loss Chest or abdominal discomfort Palpitations Nausea/vomiting Constipation Orthostatic hypotension — becoming lightheaded or dizzy after swiftly changing positions Psychiatric manifestations Anxiety, panic attacks, nervousness, tremors Hyperglycemia (high blood sugar)