Overview
Clinical Meaning
Pheochromocytomas are catecholamine producing tumors arising from chromaffin cells of the adrenal medulla (90%) or extra adrenal paraganglia (paragangliomas — 10%).
FNP
FNP
Pheochromocytomas are catecholamine-producing tumors arising from chromaffin cells of the adrenal medulla (90%) or extra-adrenal paraganglia (paragangliomas — 10%). These tumors synthesize, store, and episodically release catecholamines (norepinephrine, epinephrine, and dopamine) in massive, unregulated quantities. Norepinephrine activates alpha-1 receptors (vasoconstriction → severe hypertension) and beta-1 receptors (tachycardia, increased contractility). Epinephrine activates beta-2 receptors (vasodilation, bronchodilation, hyperglycemia via glycogenolysis) in addition to alpha and beta-1 effects. The episodic nature of catecholamine release causes paroxysmal symptoms: the classic triad of headache, diaphoresis, and palpitations with hypertension. Sustained catecholamine excess causes catecholamine cardiomyopathy (myocardial stunning, takotsubo-like syndrome, dilated cardiomyopathy), malignant hypertension, and metabolic effects (hyperglycemia, weight loss). The '10% rules' (10% bilateral, 10% extra-adrenal, 10% malignant, 10% pediatric) have been revised upward — genetic predisposition is found in 30-40% of cases (SDHx, VHL, RET, NF1 mutations).
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