What is the rule of ten in pheochromocytoma?
Classically, each of the following accounts for about 10% of all pheochromocytomas:
• Bilateral (in both adrenal glands)
• Familial (associated with multiple endocrine neoplasia [MEN] syndromes)
In reality, few large series show the expected 10% incidence; recent data suggest that about 20% of pheochromocytomas are heredofamilial (see next question).