Pheochromocytoma - Diagnosis and Management Summary
10 percent rule = 10% of pheochromocytomas are extra-adrenal, multiple, bilateral, malignant, pediatric cases, not associated with hypertension, or calcifications showing on imaging
Epidemiology
• Catecholamine-secreting neoplasms of pts with hypertension
• Annual incidence: 0.8/100,000 person-years
• 50-year autopsy series (1928-1977) -> 50% diagnosed at autopsy
• Age range: 3rd-5th decades of life
• M=F
Symptoms and Signs: 50% pts, and when present, they are typically paroxysmal.
• Classic triad: episodic headache, sweating, and tachycardia (don't trust triads)
• Hypertension: 1/2 paroxysmal HTN, most primary hypertension; some normal BP (5-15%) → incidentaloma/periodic screening for familial pheochromocytoma.
• Headache → mild or severe → 90% of symptomatic patients
• Generalized sweating → 60-70% symptomatic; forceful palpitations, tremor, pallor, dyspnea, generalized weakness, and panic attack-type symptoms.
• Pheochromocytoma crisis, or pheochromocytoma multisystem crisis → These individuals may have either hypertension or hypotension, hyperthermia (temperature >40C), mental status changes, and other organ dysfunction.
Less common symptoms and signs:
• Orthostatic hypotension (may reflect low plasma volume) and others —i visual blurring, papilledema, weight loss, polyuria, polydipsia, constipation, increased erythrocyte sedimentation rate, insulin resistance, hyperglycemia, leukocytosis, psychiatric disorders, and, rarely, secondary erythrocytosis due to overproduction of erythropoietin
• Cardiomyopathy → cardiomyopathy attributed to catecholamine excess that is similar to stress-induced (takotsubo) cardiomyopathy; may present with pulmonary edema (deteriorate w/ initiation of beta-adrenergic blockade.
• Paroxysmal elevations in blood pressure → pheochromocytoma when paroxysmal elevations in blood pressure (hypertension, tachycardia, or arrhythmia) during diagnostic procedures (eg, colonoscopy), induction of anesthesia, surgery, with certain foods or beverages containing tyramine, or with certain drugs (such as beta-adrenergic blockers, tricyclic antidepressants, corticosteroids, metoclopramide or monoamine oxidase inhibitors).
• Abnormalities in carbohydrate metabolism (insulin resistance, impaired fasting glucose, apparent type 2 diabetes mellitus) are directly related to the increase in catecholamine production.
Treatment
• Operable disease: Management consists of preoperative blood pressure management and then surgery.
• Preoperative blood pressure management: combined alpha and beta-adrenergic blockade - First, a non-selective alpha blocker is given: phenoxybenzamine blocks alpha-1 and alpha-2 adrenoceptors equally and irreversibly. After sufficient alpha-adrenergic blockade, a beta blocker may be started for additional blood pressure control and control of tachyarrhythmias.
• Treatment of choice: laparoscopic tumor resection (adrenalectomy). "No-touch" technique. Open surgical resection is reserved for large or invasive tumors. Starting beta blockers before alpha blockade is contraindicated.
• Beta blockers cancel out the vasodilatory effect of peripheral beta-2 adrenoceptors, potentially leading to unopposed alpha-adrenoceptor stimulation, causing vasoconstriction and ultimately hypertensive crisis.
• Benign pheochromocytoma: primary therapy with phenoxybenzamine
• Malignant pheochromocytoma: MIBG therapy ; otherwise, palliative Treatment (chemotherapy, tumor embolization)
- Dr. Jorge Cortés @Jcortesizaguirr
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