Rare tumor arising in catecholamine-secreting chromaffin cells of the adrenl medulla.
Often benign; symptoms include those associated with increased secretion of catecholamines (hypertension, nervousness, tachycardia, sweating, trembling).
If left uncorrected (e.g. by surgical removal of the tumor), hypertension due to sustained production of catecholamines can prove fatal.
Remember 10% when you think of a pheochromacytoma: 10% are bilateral, 10% are in children, 10% are malignant.