This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Parathyroid and adrenal glands, Subject name: Surgery
All are true about pheochromocytoma except: 
Select and explain. 
A. 90% are malignant, B. 95% occur in the abdomen, C. They secrete catecholamines, D. They arise from sympathetic ganglions
A: 90% are malignant
Answer: A: 90% are malignant 
Explanation: Only 10% are malignant. They are also called 10 % tumors because 10% are bilateral, 10% are extra adrenal, 10% occur in pediatric patients, 10% are familial. One "traditional" 10% rule that has now been modified peains to familial cases. It is now recognized that as many as 25% of individuals with pheochromocytomas and paragangliomas harbor a germline mutation in one of at least six known genes