PHEOCHROMOCYTOMA

Introduction

Pheochromocytomas are neoplasms of the chromaffin cells of the adrenal medulla or paraganglial cells of extramedullary sites (paragangliomas) 

-These tumors secrete excessive amounts of epinephrine, norepinephrine, or both or even dopamine

-Most pheochromocytomas secrete norepinephrine 

-Pheochromocytoma was classically referred to as the “tumor of tens” because it was considered that 10% are hereditary, 10% are malignant, 10% are asymptomatic, 10% are extra-adrenal, 10% are extra-abdominal,10% are multiple, 10% are bilateral

– They can occur at any age, have no gender predilection

-Peak incidence: in the fourth and fifth decades of life

-Familial causes: Multiple Endocrine Neoplasia type 2 (MEN 2), von Hippel-Lindau disease, von Recklinghausen neurofibromatosis type 1 (NF-1) 

Symptoms & Signs 

-The classic pentad of symptoms: Episodic headache, palpitations, unusual sweating, pallor and orthostasis

-Other symptoms: Anxiety, irritability, flushing, chest pain, shortness of breath, nausea, vomiting, abdominal pain

-The most common clinical sign: Hypertension 

-Typical paroxysm: Sudden headache, palpitations, and sweating produced by anxiety or activities that compress the tumor (bending, defecation, deep palpation of the abdomen etc) 

Diagnosis 

24-hour urinary tests: Catecholamines, Fractionated metanephrines, total metanephrines

Plasma tests: Catecholamines, Free metanephrines

Imaging: CT, MRI, MIBG scintigraphy, Somatostatin receptor scintigraphy

Most sensitive test: Plasma fractionated free metanephrines

Most specific test: Urinary total metanephrines 

Treatment 

Definitive treatment: Surgery 

First administer alpha blockers, then beta blockers

α-blockers: Phenoxybenzamine, prazosin, terazosin, doxazosin

beta blockers: Propranolol, atenolol, metoprolol, carvedilol, bisoprolol, esmolol 

Calcium channel blockers: Nicardipine 

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