This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology and breast, Subject name: Surgery
After bilateral adrenalectomy, patient developed gradual loss of vision, with hyperpigmentation of skin, and headache. Likely cause is 
Select and explain. 
A. Addison's disease, B. Nelson's syndrome, C. Cushing's disease, D. Harrisons syndrome
B: Nelson's syndrome
Answer: B: Nelson's syndrome 
Explanation: In 10% of patients with Cushing's disease who undergo a bilateral adrenalectomy after failed pituitary surgery, the pituitary adenoma causes Nelson's syndrome due to continued ACTH secretion at high levels, causing hyperpigmentation as a result of chemical synergies between ACTH and melanocyte-stimulating hormoneRef: Bailey and Love 27e pg: 842