THU531 A Case Of Cushing Syndrome Due To Ectopic ACTH Secreting Lung Neuroendocrine Tumor Treated With Cryoablation

Disclosure: S. Paknikar: None. J. McHugh: None. K. Rachmasari: None. I. Bancos: None. Introduction: Ectopic secretion of adrenocorticotropic hormone (ACTH) is a rare and severe form of Cushing Syndrome (CS) that requires an urgent specialized approach for diagnosis and management. Clinical Case: A 50-year-old woman was referred to endocrinology due to concern for CS. Over the previous year she had developed progressive weakness, edema, weight gain with abdominal fat redistribution, hypertension, and multiple compression fractures. On exam, she had a profound proximal myopathy, reported 10/10 pain along the spine, and was hypertensive (170/105 mm Hg) with normal other vitals. The patient's sodium was 141mmol/L [reference range 135-145 mmol/ L], potassium 4.1 mmol/L [3.6-5.2 mmol/L] while on spironolactone, and creatinine was 0.57 mg/dL [0.59-1.04 mg/dL]. Due to the severity of her symptoms, she was admitted to the hospital. Hormonal work up was consistent with an ACTH dependent CS: ACTH was 121pg/mL [7.2-63 pg/mL] and 24-hour urine cortisol was 645 mcg/24 hr [3.5-45 mcg/24 hr]. Workup for ACTH secreting tumor included a pituitary MRI which showed a 3 mm area of delayed enhancement in the pituitary gland, felt to be artifactual. A chest computed tomography (CT) showed a 1.3 cm low-density nodule in the right upper lobe concerning for a neuroendocrine tumor. A Gallium-68 DOTATATE Positron emission tomography/CT scan was performed and demonstrated that the nodule was highly DOTATATE avid (Krenning score of 3, scale of 0-4). These findings supported a diagnosis of ectopic CS caused by an ACTH secreting lung neuroendocrine tumor. Management of ectopic CS was twofold: addressing the underlying ACTH secreting lesion and urgent treatment of hypercortisolism and its consequences. In this case, this was achieved with CT-guided cryoablation of the right upper lobe nodule. The ACTH levels were monitored postoperatively, and when decreased (9.3pg/mL [ 7.2-63 pg/mL], glucocorticoid replacement therapy was initiated. As a result of prolonged hypercortisolism, the patient experienced multiple compression fractures and debility. Physical therapy was recommended for recovery from the compression fractures as well as proximal myopathy. Enoxaparin was initiated due to risk of venous thromboembolism from CS. From an osteoporosis standpoint, she was continued on calcium and vitamin-D supplementation and treated with weekly alendronate. Her hypertension improved allowing medication reduction. Postoperatively, she received education on adrenal insufficiency and biochemical monitoring for adrenal insufficiency recovery was implemented. Conclusion: Ectopic ACTH secreting tumors represent a rare cause of CS and effective management requires consideration of medical comorbidities to determine the approach: surgical, cryoablative, or medical therapy alone, mitigation of Cushing syndrome sequelae, and prompt recognition and treatment of glucocorticoid withdrawal. Presentation: Thursday, June 15, 2023