A patient has Cushing's syndrome with an 8 mm ACTH-secreting pituitary adenoma confirmed on MRI. The IPSS (inferior petrosal sinus sampling) ACTH gradient is 3.5 (normal >2). Despite two attempts at trans-sphenoidal surgery, hypercortisolism persists. Which is the BEST next step?
- A Bilateral adrenalectomy
- B Stereotactic radiosurgery (Gamma Knife) ✓
- C Repeat MRI and wait 6 months
- D Add high-dose ketoconazole indefinitely
Correct answer: B. Stereotactic radiosurgery (Gamma Knife)
Explanation
In persistent Cushing's disease after failed repeat trans-sphenoidal surgery, stereotactic radiosurgery (Gamma Knife) is the preferred second-line surgical modality; it achieves remission in 50–55% of cases over 2–3 years. Bilateral adrenalectomy is reserved for patients who fail radiosurgery or require rapid cortisol control, and carries the risk of Nelson's syndrome. Ketoconazole is a bridge therapy but not definitive treatment.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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Written and medically reviewed by the StethoPrep medical team.