[Intraosseous paraganglioma of the sacrum: a case report].

137 The paraganglion system, a component of the neuroendocrine system, comprises the adrenal medullae and the extra-adrenal paraganglion system. Tissues of the extra-adrenal system have been classified into 4 groups: branchiomeric (associated with arterial vessels and cranial nerves derived from the branchial arches); intravagal; aorticosympathetic; and visceral-autonomic (including cardiac atria, bladder, liver hilum and mesenteries). Tumours, or paragangliomas, may arise anywhere in this system. Paragangliomas have also been reported to have arisen in locations where paraganglia are not normally found, such as the duodenum, stomach, vulva, spinal cord, filum terminale and cauda equina. The majority of paragangliomas are nonfunctional and benign; however, they may secrete catecholamines or have malignant potential.