To characterize the symptoms associated with pheochromocytoma and discuss the diagnosis and management of this tumor.We review the clinical manifestations in patients with pheochromocytoma, the biochemical and imaging studies recommended for diagnosis and localization of the tumor, and the available strategies for treatment.Pheochromocytoma is a tumor of chromaffin cells that originates in either the adrenal medulla or the extra-adrenal sympathetic tissues. It is usually unilateral and benign. Frequent initial symptoms include headache, sweating, and palpitations, with or without increased blood pressure. In many patients, hypertension is accelerated during a paroxysm. Pheochromocytoma may also occur as a part of multiple endocrine neoplasia type IIA and B. Several common syndromes, such as panic disorders and hyperthyroidism, may mimic pheochromocytoma; however, pheochromocytoma should be suspected in the presence of hypertension, tachycardia, and throbbing headache, especially occurring as paroxysmal episodes. The physiologic diagnosis of pheochromocytoma is established by biochemical tests of levels of plasma and urinary catecholamines or their metabolites (or both). In most patients, anatomic localization is achieved with computed tomography or magnetic resonance imaging, metaiodobenzylguanidine scintigraphy, labeled somatostatin scans, or positron emission tomography. The management preferentially includes surgical removal of the pheochromocytoma after preparation with appropriate medical therapy to avoid hypertensive crisis during the perioperative period. Patients with contraindications to a major surgical procedure or with malignant pheochromocytoma and metastatic disease, however, may be treated with multiple drugs--for example, alpha- and beta-adrenergic blockers and direct vasodilators to neutralize the effects of high levels of circulating catecholamines and alpha-methyl-metatyrosine to inhibit catecholamine synthesis.The presence of suggestive clinical features in patients with hypertension should prompt clinicians to undertake appropriate diagnostic testing because surgical resection of a pheochromocytoma will yield a cure in many cases.