SUN-390 A Rare Case of Bilateral Macronodular Adrenal Hyperplasia Discovered Incidentally

Introduction: Asymptomatic adrenal masses are often discovered incidentally while testing for unrelated conditions. A very uncommon finding is thickening and increased nodularity of both adrenal glands, which can lead to the patient being diagnosed with subclinical Cushing's syndrome, Conn's syndrome, or both. Case presentation: A 45-year-old African-American man presented to the hospital with a one-month history of increased abdominal girth, bilateral lower extremity edema and shortness of breath, with progressive epigastric abdominal pain which prompted admission. His medical history was relevant for obesity, coronary artery disease and heart failure with reduced ejection fraction. On examination he had a blood pressure of 152/99 mmHg, was diaphoretic, and complained of constant epigastric pain. Multiple purple and pale striae were visible along his abdomen, and he had pitting edema in both lower extremities. His initial laboratory studies showed a potassium of 2.6 mEq/L. A CT scan of the abdomen was relevant for bilaterally enlarged and tortuous adrenal glands, which the patient had no previous knowledge of. Diuresis greatly improved his edema and shortness of breath. Additional laboratory tests showed persistent hypokalemia, normal plasma renin activity and aldosterone, elevated fasting cortisol, normal metanephrines in 24-hour urine collection, and low ACTH level. A suppression test done by administering dexamethasone 0.5 mg every 6 hours for 2 days, was able to suppress the elevated cortisol levels. He was started on spironolactone, and underwent MRI of the abdomen, which confirmed bilateral multinodular adrenal hyperplasia with no imaging characteristics of pheochromocytoma. The patient was discharged home once his clinical status improved. Laboratory studies done at follow-up appointments showed persistently elevated cortisol, normal aldosterone to renin ratio, normal levels of plasma metanephrines and suppressed levels of ACTH. He was also referred to surgery for eventual bilateral adrenalectomy. Discussion: Primary bilateral macronodular adrenal hyperplasia (BMAH) is a very rare cause of endogenous Cushing's syndrome, representing less than 2% of cases. It is characterized by enlarged adrenal glands containing pigmented nodules that secrete excess cortisol and/or aldosterone (1). BMAH is often an incidental finding in patients with subclinical hyper-cortisolism. A low level of plasma ACTH along with bilaterally enlarged adrenal glands on imaging suggest the diagnosis, and this is confirmed with a dexamethasone suppression test. Accurate detection is important for guiding management, which includes pharmacological therapy and bilateral adrenalectomy. Reference: 1. De Venanzi A, Alencar GA, Bourdeau I, Fragoso MCBV, Lacroix A. Primary bilateral macronodular adrenal hyperplasia. Curr Opin Endocrinol Diabetes Obes. 2014 Jun;21(3):177-84.