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
Which of the following is not a CT feature of adrenal adenoma? 
Select and explain. 
A. Low attenuation, B. Homogeneous density and well defined borders, C. Enhances rapidly, contrast stays in it for a relatively longer time and washes out late, D. Calcification is rare
C: Enhances rapidly, contrast stays in it for a relatively longer time and washes out late
Answer: C: Enhances rapidly, contrast stays in it for a relatively longer time and washes out late 
Explanation: Adrenal adenoma on contrast enhanced CT/MRI show rapid uptake and relatively rapid washout of contrast material than non adenomas. CT Features of Adrenal Adenoma Well defined /sharply defined <5 cm in size Low attenuation (< 10 HU) due to lipid content Mild homogenous enhancement Relatively rapid washout of contrast material (due to lack of large interstitial spaces) Relatively rapid washout is characteristic of adenoma