Endocrine Abstracts

Introduction: In severe Cushing’s disease, first-line treatment is transsphenoidal surgery, with repeat surgery or radiotherapy if remission is not achieved, and medical management if necessary. If these options fail, bilateral adrenalectomy is considered. Nelson’s syndrome is defined as continuous secretion of ACTH by pituitary tumour after adrenalectomy. Discontinuing hydrocortisone risks adrenal crisis but may also stimulate the growth of corticotrophinoma.

Case Report: A 36-year-old male diagnosed with Cushing’s disease at age 10 underwent transsphenoidal adenomectomy in 2002 and pituitary radiotherapy in 2003, both failing to achieve remission. Bilateral adrenalectomy followed in 2006, with hydrocortisone and fludrocortisone replacement. Lost to follow-up in 2011, he re-presented in 2021 with hyperpigmentation, hypertension, pre-diabetes, obesity, and obstructive sleep apnoea, off hydrocortisone for five years without adrenal crisis. Imaging identified a growing pituitary macroadenoma (14x18 mm), larger than in 2011 (7x6 mm), and a CT showed an 18 mm adrenal remnant. His ACTH was 436 ng/l, and cortisol was 335 nmol/l after 20 hours without hydrocortisone. Following a failed Synacthen test, hydrocortisone and fludrocortisone were resumed. In 2022, a second transsphenoidal surgery confirmed a corticotroph PITNET. Post-operative MRI showed a 10x8 mm residual tumour near the optic chiasm, making further radiosurgery unsafe. Persistently elevated ACTH and repeated Synacthen test failure (cortisol 248-330nmol/l) indicated ongoing adrenal insufficiency despite functional adrenal tissue. He remains under annual MRI and biochemical monitoring.

Conclusion: This case demonstrates that even after five years without hydrocortisone, an adrenal crisis may not occur if even a small volume of functional adrenal tissue remains. It highlights the complexity of Cushing’s disease and the need for strict specialist MDT follow-up.