Paraganglioma is a tumor that is closely related to Pheochromocytoma. It originates from outside the adrenal glands, specifically from the parasympathetic or sympathetic nervous system. Paragangliomas are much less common than pheochromocytomas. Just like pheochromocytoma, paraganglioma is also characterized by the presence of an excess amount of hormones called catecholamines, which include metanephrine, norepinephrine (noradrenaline), epinephrine (adrenaline), and dopamine. Some pheochromocytomas or paragangliomas, although very few, can be biochemically silent, thus do not produce any catecholamines.
Paragangliomas are most often located in the head and neck region, chest, abdomen, or pelvis. Paragangliomas are more likely to be cancerous than pheochromocytomas.