This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pediatrics
What percentage of pheochromocytomas are malignant? 
Select and explain. 
A. 5, B. 10, C. 20, D. 15
B: 10
Answer: B: 10 
Explanation: b. 10(Ref: Nelson's 20/e p 2227-2729, Ghai 8/e p 525)Mnemonic:'Rule of ten' for Pheochromocytoma: ("BG MEN"): 10% of Pheochromocytoma are:* Bilateral* Malignant* Extra-adrenal: paragangliomas* Normotensive (No hypertension)Note: 10% of sporadic Pheochromocytoma are bilateral; but 50% of familial tumors are bilateral.