This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Physiology and Pathophysiology - Secondary & Tertiary Hyperparathyroidism, Subject name: Surgery
Enlargement of pituitary tumor after adrenalectomy is called as? 
Select and explain. 
A. Nelson s syndrome, B. Steel Richardson syndrome, C. Hamman rich syndrome, D. Job s syndrome
A: Nelson s syndrome
Answer: A: Nelson s syndrome 
Explanation: ANSWER: (A) Nelson s syndromeREF: Schwartzs Principles of Surgery 9th edition chapter 38. Thyroid, Parathyroid, and Adrenal "Nelson's syndrome is the rapid enlargement of a pituitary adenoma that occurs after the removal of both adrenal glands"Approximately 30% of patients who undergo bilateral adrenalectomy for Cushings disease are at risk of developing Nelson s syndromefrom progressive growth of the pre-existing pituitary tumor. This leads to increased ACTH levels, hyperpigmentation, visual field defects, headaches, and extraocular muscle palsies.