This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Incidence of adrenal incidentaloma on CT scan is: 
Select and explain. 
A. <5%, B. 5-10%, C. 10-20%, D. >25%
A: <5%
Answer: A: <5% 
Explanation: Adrenal lesions discovered during imaging performed for unrelated reasons are referred to as incidentalomas. This definition excludes tumors discovered on imaging studies performed for evaluating symptoms of hormone hypersecretion or staging patients with known cancer. The incidence of these lesions identified by CT scans ranges from 0.4 to 4.4%. Ref: Schwaz's principle of surgery 9th edition, chapter 38.