Pheochromocytoma: Tips on Diagnosis and Localization

6 New Technologies in Diabetes Mellitus Catecholamine-secreting tumors that arise from chromaffin cells of the adrenal medulla and the sympathetic ganglia are referred to as pheochromocytomas and extra-adrenal catecholamine-secreting paragangliomas (extra-adrenal pheochromocytomas), respectively. Because the tumors have similar clinical presentations and are treated with similar approaches, many clinicians use the term pheochromocytoma to refer to both adrenal pheochromocytomas and extra-adrenal catecholamine-secreting paragangliomas. However, the distinction between pheochromocytoma and paraganglioma is an important one because of implications for associated neoplasms, risk of malignancy, and genetic testing. Catecholamine-secreting tumors are rare, with an annual incidence of 2 to 8 cases per 1 million people in all populations studied. William F. Young Jr, MD, of the Division of Endocrinology, Diabetes, Metabolism, and Nutrition at Mayo Clinic in Rochester, Minnesota, says: “Nevertheless, it is important to suspect, confirm, localize, and resect these tumors because 1) the associated hypertension is curable with surgical removal of the tumor, 2) a risk of lethal paroxysm exists, 3) at least 10% of the tumors are malignant, and 4) 10% to 20% are familial and detection of this tumor in the proband may result in early diagnosis in other family members.” In 2009, pheochromocytoma is frequently diagnosed before symptoms develop because of genetic screening for hereditary endocrine syndromes or incidental discovery of adrenal mass on computed tomography (CT) or magnetic resonance imaging (MRI). Clive S. Grant, MD, of the Department of Surgery at Mayo Clinic in Rochester, says: “In many patients, catecholamine-synthesizing neoplasms are detected months or years before the onset of periodic hypersecretory states. Approximately 5% of all adrenal incidentalomas have proved to be pheochromocytomas. In the past, it was said that more than 95% of patients with pheochromocytoma had paroxysmal symptoms (spells) of palpitations, diaphoresis, and headaches. However, with the widespread use of CT and MRI, approximately 50% of all pheochromocytomas are initially detected as adrenal incidentalomas in patients without spells and, frequently, without hypertension.” Dr Grant continues: “It is important to recognize that in a patient with spells, the degree of increase in fractionated metanephrines and catecholamines in the blood or urine should be markedly abnormal. In other words, if a pheochromocytoma is responsible for ‘classic pheochromocytoma spells,’ then the biochemical test results are always unequivocally Pheochromocytoma: Tips on Diagnosis and Localization