Pheochromocytomas are rare catecholamineproducing neuroendocrine tumors arising from the chromaffin cells of the adrenal medulla (80%-85%) or extra-adrenal paraganglia (15%-20%). The secretory profiles of these tumors vary but predominately secrete norepinephrine (NE) with lesser amounts of epinephrine (EPI). The prevalence of pheochromocytoma in the outpatient hypertensive population is reported to be somewhere between 0.1% and 0.9%; about 25% are discovered incidentally during imaging studies for unrelated disorders.
1The clinical presentation of pheochromocytomas can vary greatly but is typically described as spells with the classic triad of tachycardia, headaches, and diaphoresis occurring in at least 25% of cases. Severe hypertension is usually present during the attacks. Other symptoms can include pallor; tremulousness; orthostatic hypotension, especially in the morning (that may reflect a low plasma volume); visual blurring; papilledema; weight loss; polyuria; and polydipsia. Several medications, including opiates, metoclopramide, tricyclic antidepressants, and anesthesia can induce pheochromocytoma-related hypertension. Hypertension and ⁄ or hypertensive spikes are the result of catecholamines on the cardiovascular system probably coupled with enhanced sympathetic nervous system activity.The diagnosis is often not made for many years because of the fleeting episodes and nonspecific symptoms. It is usually entertained when there is a history of spells with sweating and palpitations, resistant hypertension, family history of pheochromocytoma, or incidentally discovered adrenal mass. There is no consensus on the best chemical test for diagnosing pheochromocytoma, but high sensitivities are achieved by measuring fractionated metanephrines and catecholamines in a 24-hour urine collection (97%) or fractionated plasma free metanephrines (99%). Tumor localization with computed tomography or magnetic resonance imaging should normally take place after biochemical confirmation of the pheochromocytoma.Treatment with a-blockers, usually combined with a b-blocker, prior to tumor removal decreases mortality associated with surgery.2 There is no consensus on the preferred agent, but competitive (doxazosin or prazosin) or noncompetitive and longer-acting (phenoxybenzamine) a-blockers are usually used. Alternatives are the mixed a ⁄ b-blocker labetalol, dihydropyridine calcium channel blockers, or metirosine. 1 We report on a rare presentation of pheochromocytoma with rapid alternating cycles of hypertension and hypotension successfully treated with fluid expansion and metirosine prior to tumor removal.
CASE REPORTA 47-year-old woman presented for an EPS for evaluation of palpitations. She had hypertension