SAT320 Cyclic Cushing Syndrome Caused By An ACTH-Producing Pheochromocytoma

Abstract

Abstract Disclosure: Y.B. Omotosho: None. M.E. Wierman: None. K. Bukhari: None. K. Pacak: None. R. McGlotten: None. L.K. Nieman: None. Background: Although pheochromocytomas (Pheo) predominantly produce catecholamines, they also rarely produce Adrenocorticotropin (ACTH) and present with Cushing syndrome (CS). Cyclic CS is an uncommon presentation of hypercortisolism. We here report a unique case of cyclic ectopic ACTH secretion from a Pheo. Clinical case: A 72-year-old female was referred to the NIH with a five-year history of intermittent episodes of unintentional weight gain, hair loss, skin thinning, striae, tremors, labile emotions, glucose intolerance, and a sense of impending doom, interspersed with anorexia, weight loss, normal glucose levels, headaches, and fatigue. The external evaluation documented ACTH-dependent CS with episodes of hypercortisolism, thought to be occult ectopic ACTH secretion. On admission, blood pressure ranged from 122/75 to 171/78 mmHg, and she had a Cushingoid habitus. The biochemical investigation showed basal ACTH 219 pg/ml (NL 5- 46 pg/ml); serum cortisol of 76.9 mcg/dl after 1mg dexamethasone (Dex) suppression test (NL <1.8 mcg/dl), with Dex level of 903; cortisol increased from 13.3 mcg/dl to 15.5 mcg/dl after 8mg Dex, Dex level 4680 ng/ml; plasma normetanephrine 1.8 nmol/L, (NL < 0.9 nmol/L); metanephrine 0.6 nmol/L (NL <0.5 nmol/L); norepinephrine 1493 pg/mL (NL 70-750 pg/mL); epinephrine 298 pg/mL (NL <111 pg/mL); chromogranin A 1314 ng/mL (NL <93 ng/mL). MRI pituitary was normal and bilateral inferior petrosal sinus sampling did not show a central: peripheral gradient before or after desmopressin administration. CT abdomen showed a right adrenal nodule measuring 2.3 cm x 1.8 cm, with pre-and post-contrast Hounsfield units of 30 and 106, and 54% washout. The adrenal mass showed intense activity on 68Ga-DOTATATE and 18F-DOPA PET/CT scans. The patient underwent a right adrenalectomy; the 2.7 x 2.3 x 1.5 cm mass was a Pheo with immunohistochemical staining for ACTH, chromogranin A, and synaptophysin. Post-operatively, blood pressure normalized, and medications were reduced from preoperative metoprolol, lisinopril, and doxazosin to low-dose metoprolol at discharge. Morning cortisol and ACTH levels were <1 mcg/dl and <5 pg/ml. Physiologic replacement of hydrocortisone (15 mg on awakening and 5 mg in the afternoon) was started and switched to prednisone 5mg daily for ACTH deficiency and convenience. The pituitary-adrenal axis remained suppressed at her 6-month follow-up visit. Conclusion: Cyclic CS poses a diagnostic challenge. Here, desmopressin helped to exclude Cushing's Disease. Although ACTH-producing Pheo is rare, it should be considered in the context of ACTH-dependent hypercortisolism if an adrenal mass is present. Presentation: Saturday, June 17, 2023