ABSTRACT
Pheochromocytomas are tumors of chromaffin cells located in the paraganglionic system and can occur in the adrenal glands or in the sympathetic chain.
It has been estimated that one in two million people in the United States is affected each year by extra-adrenal pheochromocytoma. Sporadic pheochromocytoma has been found in 0.002% to 0.13% of the population, and is the sole cause of hypertension in less than 1% (1,2) of all newly diagnosed hypertension. In 15% to 50% of hereditary causes, of which von Hippel-Lindau disease and multiple endocrine neoplasia type 2 are the most common types, pheochromocytoma is present (3). About 10% of pheochromocytomas are extra-adrenal, although recent reports suggest that as many as 18% may occur in extra-adrenal locations (4,5).
