SUN-435 Ectopic Cushing Syndrome, A Diagnostic and Therapeutic Challenge

Abstract M. Khan: None. B. Sharma: None. Introduction: Ectopic Cushing Syndrome (EAS) is a rare entity accounting for 5-20% of all Cushing syndrome cases. We present a case of Cushing’s syndrome with ectopic ACTH secretion from a bronchial carcinoid tumor that was a diagnostic and therapeutic challenge. Clinical Case: An 83-year-old lady with a history of Grave's Disease was hospitalized for uncontrolled hypertension and recurrent hypokalemia. She reported fatigue and muscle weakness. On examination, she had increased abdominal fat, decreased muscle mass in her arms, and Cushingoid features. 9 a.m plasma cortisol was 76.4 ug/dl (Normal (NL) 4.8-19.5 ug/dl), 24 Hour Urine Free Cortisol 44776 mcg/24 hr (NL 4-50 mcg/24 hr), and plasma ACTH 150 ng/L (NL < 50 ng/L). Plasma cortisol failed to suppress after overnight 1 mg dexamethasone 69.6 nmol/L (NL: <50 nmol/L) or after 8 mg dexamethasone 61.7 mcg/dl (NL <2 mcg/dl). MRI Brain did not reveal a pituitary lesion. CT scan of the chest/abdomen showed an incidental cyst on the pancreas and a 1.1 cm right lower lobe nodule. MRI Abdomen showed bilateral adrenal thickening. 68Ga-DOTATE PET/Computed Tomography Scan did not identify a source lesion. A Lung Biopsy showed carcinoid cells, and immunohistochemistry was positive for synaptophysin, chromogranin, and ACTH. Ketoconazole therapy preceded cryoablation of the lung lesion. Plasma ACTH decreased significantly post-cryoablation. Maintenance steroids were continued, given the concern for adrenal insufficiency. Conclusion: Differentiating pituitary Cushing syndrome (Cushing disease) from an ectopic ACTH-secreting neoplasm can be difficult. Small tumors can be difficult to detect with conventional CT scans and MRIs. Even tumors as small as 0.5 mm can produce florid Cushing's syndrome. The condition necessitates urgent control of the hypercortisolemia once the diagnosis is established (1). Ketoconazole and metyrapone have good efficacy and safety. Treatment is complete excision of the ACTH-secreting tumor (1). Ectopic ACTH-secreting tumor presentations can be a diagnostic and therapeutic dilemma that warrants multidisciplinary involvement when diagnosis and management are equivocal. Reference: 1. Kenchaiah M, Hyer S. Cushing's Syndrome due to Ectopic ACTH from Bronchial Carcinoid: A Case Report and Review. Case Rep Endocrinol. 2012;2012:215038. doi: 10.1155/2012/215038. Epub 2012 May 17. PMID: 22934197; PMCID: PMC3420587. Sunday, June 2, 2024