ten percent rule

Last reviewed 07/2023

Phaeochromocytomas may be referred to as the 10% tumour:

• 10% are extra-adrenal, most commonly, in the organ of Zuckerkandl, located in the aortic bifurcation. Less than 1% are extra-abdominal
• 10% are bilateral, increasing to 70% in familial cases
• 10% are malignant, but the risk of malignancy in women is three fold that in men
• 10% are multiple
• 10% occur in children, but 25-30% of children have extra-adrenal and/or bilateral tumours