Review Question - QID 100411

This patient's clinical presentation is consistent with pheochromocytoma, which is caused by hyperactivity of the Chromaffin cells of the adrenal medulla. In Figure A, Region 6 corresponds with the adrenal medulla.

The rule of 10 applies to these tumors: 10% are malignant, bilateral, extra-adrenal, pediatric. Patients present with palpitations, headache, and episodic diaphoresis. It is unclear why symptoms take on the characteristically episodic presentation. The tumor is diagnosed by elevated 24 hr urine catecholamines and elevated urine vanillylmandelic acid.

Hart et al. review this condition and emphasize that while it is rare, pheocromocytomas are a potentially lethal cause of hypertension that is surgically reversible. Catecholamine release is often intermittent, which can make for difficulty of diagnosis. Current management involves blocking alpha-adrenergic stimulation preoperatively.

Viera et al. present an algorithm to diagnose secondary hypertension based on age. They define secondary hypertension as a condition where hypertension occurs due to an underlying secondary cause. Thus additional symptoms (e.g. flushing and sweating suggestive of pheochromocytoma or renal bruit suggestive of renal artery stenosis) may suggest a secondary etiology contributing towards the hypertension.

Figure A shows the typical histology of a pheochromocytoma, with hyperactivity of Chromaffin cells in the adrenal medulla (#6).

Incorrect Answers:
Answer 1: Region 1 represents the connective tissue capsule.
Answer 2: Region 2 represents the zona glomerulosa. A tumor in this region would cause aldosterone overproduction.
Answer 3: Region 4 represents the zona fasciculata. A tumor in this region would cause corticosteroid overproduction and Cushing's Syndrome.
Answer 4: Region 5 represents the zona reticularis. A tumor in this regions would cause androgen overproduction.

Of note, Region 3 represents the transition between the zona glomerulosa and zone fasciculata.