Possible sites include the following: Paraganglia of the sympathetic chain Retroperitoneally along the course of the aorta Carotid body Organ of Zuckerkandl (at the aortic bifurcation) Genitourinary system Brain Pericardial sac Dermoid cysts Pheochromocytomas in the adrenal medulla occur equally in both sexes, are bilateral in 10% of cases (20% in children), and are malignant in < 10%.