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: Medicine
Which of the following is true about Nelson syndrome 
Select and explain. 
A. Occurs after adrenalectomy, B. Pituitary harmones are decreased, C. Hyper pigmentation, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: After bilateral adrenalectomy due to increased ACTH levels hyper pigmentation is seen. Pituitary tumor enlargement along with low pituitary harmones is present.