Pheochromocytoma

Pheochromocytomas are neoplasms of the neural crest derived chromaffin cells.Synthesis and secretion of catecholamines in an unregulated and often lifethreatening manner is the hallmark of this rare tumor. Chromaffin cells are most frequently found in the adrenal medulla,where they normally function to secrete catecholamines,which modulate stress response, metabolism, and blood pressure.When catecholamineproducing chromaffin cell tumors arise in an extra-adrenal location they are referred to as paragangliomas, or extra-adrenal pheochromocytomas. Although apparently similar in ontogeny,subtle differences exist in the biology of disease between adrenal and extra-adrenal pheochromocytomas,which impact clinical decision making.A thorough understanding of the natural history of the various manifestations of chromaffin cell tumors guides the clinician in the most appropriate and efficacious treatment. Although considered rare, the importance of screening for and treating pheochromocytomas is underscored by the fact that it is one of the few curable causes of hypertension, with a prevalence in hypertensive patients of 0.1-1% [36]. In autopsy series, a prevalence between 0.3% and 0.95% has been found [46]. In biochemical screening series the prevalence has been reported to be as high as 1.9% [44].Undiagnosed and untreated pheochromocytomas lead to significant cardiovascular and oncologic morbidity and mortality.