Pheochromocytoma: diagnostic and therapeutic update

Pheochromocytomas are catecholamine-secreting tumors that arise from chromaffin cells of the sympathetic nervous system. In 80-85% of cases, these tumors are located in the adrenal medulla while the remainder is located in extra-adrenal chromaffin tissues (paragangliomas). Pheochromocytomas account for 6.5% of incidentally discovered adrenal tumors. These tumors may be sporadic or the result of several genetic diseases: multiple endocrine neoplasia type 2, von Hippel-Lindau syndrome, neurofibromatosis type 1, and familial paraganglioma associated with mutations in succinate dehydrogenase subunits. Diagnosis of pheochromocytoma should first be established biochemically by measuring plasma free metanephrines and urinary fractionated metanephrines. The radiological imaging tests of choice are computed tomography (CT) or magnetic resonance imaging (MRI). The first-line specific functional imaging test is scintigraphy with (123)I-metaiodobenzylguanidine (MIBG); if this test is unavailable, scintigraphy with (131)I-MIBG is the second choice. Positron emission tomography (PET) with (18)F-F-fluorodopamine (F-DA) is useful in metastatic disease. The treatment of choice is laparoscopic surgery after adequate alpha adrenergic blockade. Approximately 10% of tumors are malignant. Chemotherapy is used for inoperable disease. Prognosis is good except in malignant disease, in which 5-year survival is less than 50%. The identification of the genes causing hereditary pheochromocytoma has led to changes in the recommendation for genetic testing.