Pheochromocytoma

Small clusters of tumor cells with amphophilic cytoplasm are separated by a highly vascular stroma. Pheochromocytomas vary in their enzymatic activity and in their ability to self-metabolize catecholamines. This accounts for the heterogeneity in the levels of epinephrine, norepinephrine, and dopamine produced by different pheochromocytomas which is ultimately reflected in the clinical behavior. Patients with predominantly epinephrine producing tumors usually present with syncope and hypotension, whereas those with norepinephrine producing tumors present with hypertension, sweating, and tachycardia.