Pheochromocytoma

Pheochromocytoma is a neuroendocrine tumor arising from chromaffin cells, most commonly in the adrenal medulla (90%), though extra-adrenal tumors (paragangliomas) occur in 10%. The tumor produces catecholamines (epinephrine and norepinephrine) that cause the characteristic symptoms. Episodic catecholamine release causes sudden hypertensive attacks with severe headache, sweating, palpitations, and anxiety. Attacks can be triggered by abdominal pressure, exercise, micturition, foods containing tyramine, or occur spontaneously. The rule of 10s classically applied: 10% bilateral, 10% familial, 10% malignant, 10% extra-adrenal, 10% in children. However, newer genetic and imaging data suggest higher rates of hereditary disease. Sustained hypertension or episodic hypertension with normal blood pressure between attacks both occur. Untreated tumors increase risk of myocardial infarction, stroke, cardiomyopathy, and sudden cardiac death. Long-term catecholamine excess can cause irreversible complications. About 10% are malignant with metastatic potential, particularly SDH mutation-associated tumors. Genetic testing is recommended for all patients to identify hereditary syndromes.