Unexplained symptomatic paroxysmal hypertension in pseudopheochromocytoma: a stress response disorder?

Among overall numbers of patients tested for pheochromocytoma, less than 2% harbor the tumor. Among the rest, there is often no satisfactory explanation for the signs and symptoms leading to suspicion of pheochromocytoma. This group includes patients with severe symptomatic paroxysmal hypertension, often referred to as pseudopheochromocytoma, a condition that can be debilitating for patients and perplexing for clinicians. Similar to patients with the real tumor, patients with pseudopheochromocytoma can be misdiagnosed with panic disorder. However, pseudopheochromocytoma is characterized by an absence of panic or emotional distress preceding the onset of hypertension and symptoms of catecholamine excess. Because the clinical manifestations of pseudopheochromocytoma are similar, if not identical, to those due to excess circulating catecholamines in patients with the tumor, the most attractive explanation for the disorder is that it involves altered function of the autonomic nervous system. In line with this hypothesis, recent findings suggest that enhanced adrenal release of epinephrine and exaggerated cardiovascular responsiveness to catecholamines both contribute to the paroxysmal hypertension and symptoms of catecholamine excess in pseudopheochromocytoma. From this pattern, one would predict that therapeutic interventions that inhibit adrenal secretion of epinephrine or block adrenoceptor-mediated responses to catecholamines might provide a logical approach to therapy.