9388 Unusual Case Of Ectopic Adrenocorticotropic Hormone Syndrome Secondary To Non-small Cell Lung Cancer

Abstract Disclosure: A. TakallooBakhtiari: None. G.L. Nunlee-Bland: None. V. Ganta: None. A. Zenebe: None. H. Abdalla: None. A. Elobeid: None. W.A. Odonkor: None. Introduction: Ectopic adrenocorticotropic hormone syndrome (EAS) is a rare condition due to adrenocorticotropic hormone (ACTH) release from non-pituitary tumors. It increases the mortality of affected patients thus finding and removal of the ACTH-producing source allows for curing or reduction of symptoms and serum cortisol levels. The most common cause of EAS is lung cancer. Cushing syndrome (CS) due to EAS is an uncommon paraneoplastic phenomenon in non-small cell lung cancer. Clinical case: The patient is an 80-year-old man with a past medical history of hypertension, dementia, stroke, schizophrenia, and recently diagnosed lung adenocarcinoma. He presented with a few weeks history of dysuria and generalized fatigue. There was no family history for any endocrine disorders. He has a 40 pack-year history of tobacco use. He denied alcohol or illicit drug use. Upon initial evaluation, VS: BP 155/95 mmHg, HR 82 beats/min, Ht 77 inches, Wt 125 lb with a BMI 14.7 Kg/m2. He had no typical symptoms of CS. A physical exam showed a cachectic man with no other remarkable findings. Laboratory tests on admission showed severe hypokalemia of 1.8 mEq/L (3.5-5 mEq/L) with hypochloremic metabolic alkalosis. (bicarbonate 45 mEq/L (22-28 mEq/L) and chloride 79 mEq/L (96-106 mEq/L)). Patient was normoglycemic with HbA1c of 5.0%. Random morning cortisol was 55 μg/dL (13-24 μg/dL). Supine renin and aldosterone levels were 0.45 ng/ml/h (0.25-5.8 ng/ml/h) and 1.0 ng/dL (3-16 ng/dL), respectively, excluding hyperaldosteronism. Beside urinary tract infection, other biochemical workup revealed elevated 24-h urinary free cortisol level 5233 mcg/24h (4.0-50.0 mcg/24h) with creatinine 0.7 g/24h (0.5-2.15 g/24h). Failure to suppress cortisol with low dose dexamethasone suppression test (LDDST) was evident: morning cortisol >60.0 g/dL , with concurrent serum dexamethasone 299 ng/dL (180-550 ng/dL). Plasma ACTH level was elevated 327 pg/ml (6-50 pg/ml), favoring ACTH-dependent CS. A magnetic resonance imaging (MRI) of the sella and computed tomography (CT) of the abdomen did not show pituitary or adrenal masses. Therefore, a diagnosis of ectopic CS due to lung cancer was established. Pathology of the lung mass showed tumor cells were negative for synaptophysin, chromogranin, and CD52. The immunohistochemically findings support primary adenocarcinoma of the lung. Patient refused surgical or medical treatment and was discharged to a hospice facility. Conclusion: The clinical presentation of EAS ranges from the abrupt onset of the signs and symptoms of severe hypercortisolism, including hypertension, hypokalaemia, metabolic alkalosis as in our patient to the gradual and slow onset of the classical signs and symptoms of CS. Though EAS with adenocarcinoma of the lung is rare, it is important to consider it within the differential diagnosis of any adenocarcinoma of the lung presenting with the relevant symptoms. Presentation: 6/3/2024