Endocrine Abstracts

A 26-year-old woman presented with progressive features of Cushing syndrome, including weight gain, amenorrhea, proximal muscle weakness, and purple striae. Biochemical testing revealed elevated morning serum cortisol concentrations (31 mg/dL [855 nmol/l]) and nonsuppressible cortisol on low-dose dexamethasone suppression test. Plasma ACTH was markedly elevated (121 pg/mL [26.6 pmol/l]). High-resolution computed tomography of the chest identified a lesion in the left lower lobe, and octreotide scintigraphy confirmed uptake consistent with a neuroendocrine tumor. Resection specimen demonstrated a typical carcinoid tumor immunoreactive for ACTH and CD56. Following lobectomy, the patient required hydrocortisone replacement due to hypothalamic–pituitary–adrenal axis suppression. Postoperative urinary free cortisol normalized, and ACTH decreased to 32 pg/mL (7.1 pmol/l). This case emphasizes the importance of considering ectopic ACTH syndrome in patients with hypercortisolism and negative pituitary imaging, and highlights the value of multidisciplinary management.