Challenges in Diagnosing Pheochromocytoma

A pheochromocytoma is a tumour of chromaffin cells of the sympathetic nervous system. Due to its propensity to produce and secrete catecholamines, this disease usually presents with hypertension and other symptoms of catecholamine excess. Although pheochromocytomas are very rare, a tragic outcome can result if the condition is not diag-nosed and treated appropriately since fatal cardiovascular events can occur. Furthermore, 10%-13 % of pheochromocytomas are malignant. This issue of Endocrinology Rounds will focus on the challenges in making an accurate diagnosis of pheochromocytoma, review several recent studies related to its diagnosis, and suggest an approach to minimize the risk of making an incorrect diagnosis (trying to reduce both false positive and false negative diagnoses). Pheochromocytoma is easy to diagnose when a patient presents with episodes of the classic triad of headache, palpitations, and perspiration, has hypertension, and elevated urinary levels of both catecholamines (Figure 1) and their metabolic byproducts, metanephrines (Figure 2). It is more challenging, however, when the presentation is non-classic and urinary tests are positive. How can you discriminate true positives from the fals