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General Surgery · Breast and endocrine surgery: Nelson syndrome
Sample itemA woman who underwent bilateral adrenalectomy for Cushing disease develops progressive skin hyperpigmentation, headaches and bitemporal hemianopia. What is the cause?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
A. Growth of a pituitary corticotroph adenoma
After bilateral adrenalectomy for pituitary-dependent Cushing disease, loss of cortisol feedback allows the corticotroph adenoma to enlarge and secrete large amounts of ACTH and related peptides. This is Nelson syndrome, with hyperpigmentation and visual field loss from chiasmal compression.
Option by option
A. Growth of a pituitary corticotroph adenoma (correct)
Correct. An enlarging ACTH-secreting pituitary adenoma explains pigmentation and the visual field defect.
B. Inadequate glucocorticoid replacement alone
Inadequate replacement causes adrenal insufficiency symptoms and does not produce a field defect.
C. Recurrent cortisol secretion from an adrenal remnant
An adrenal remnant would give recurrent cortisol excess and not hyperpigmentation with a field defect.
D. Ectopic ACTH secretion by a lung tumour
An ectopic ACTH source would have been the reason for the original Cushing syndrome and does not give chiasmal compression.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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