A neural crest tumor usually derived from the chromoreceptor tissue of a paraganglion, such as the carotid body, or medulla of the adrenal gland (usually called a chromaffinoma or pheochromocytoma). It is more common in women than in men. (Stedman, 25th ed; from Segen, Dictionary of Modern Medicine, 1992)
A benign or malignant neoplasm arising from paraganglia located along the sympathetic or parasympathetic nerves. Infrequently, it may arise outside the usual distribution of the sympathetic and parasympathetic paraganglia. Tumors arising from the adrenal gland medulla are called pheochromocytomas. Morphologically, paragangliomas usually display a nesting (Zellballen) growth pattern. There are no reliable morphologic criteria to distinguish between benign and malignant paragangliomas. The only definitive indicator of malignancy is the presence of regional or distant metastases.
A rare, usually benign tumor that develops from cells of the paraganglia. Paraganglia are a collection of cells that came from embryonic nervous tissue, and are found near the adrenal glands and some blood vessels and nerves. Paragangliomas that develop in the adrenal gland are called pheochromocytomas. Those that develop outside of the adrenal glands near blood vessels or nerves are called glomus tumors or chemodectomas.