ODP018 A Case of Cushing's Syndrome due to Primary Bilateral Macronodular Adrenal Hyperplasia

Abstract

Introduction

Primary bilateral macro-nodular adrenal hyperplasia (PBMAH) is a rare cause of Cushing's syndrome, characterized by a high clinical heterogeneity, both with regards to the severity of cortisol excess and the morphologic appearance of the adrenals. We present an interesting case of Cushing's syndrome caused by Primary bilateral macro-nodular adrenal hyperplasia.

Case presentation

A 61-year-old female with Graves’ disease status post I-131 therapy was incidentally found to have two left adrenal adenomas of sizes 2 cm and 1.9 cm on CT imaging. Her laboratory workup revealed Cushing's syndrome evidenced by abnormal 1 mg dexamethasone suppression test (DST) with cortisol of 7.8 mcg/dl (8-19 mcg/dl), 24-hour urinary cortisol (UFC) of 50 mcg/24hr (0-50 mcg/24hr) with ACTH 6.2 pg/ml (7.2 -63 pg/ml) and DHEAS 79.8 mcg/dl (29.4-215 mcg/dl). Her MRI brain revealed meningioma and she underwent gamma knife therapy. Over time she developed uncontrolled hypertension, pre-diabetes, weight gain and easy bruising. On examination she has a plethoric face, ruddy complexion, and central obesity. Her repeat blood work showed 1 mg DST cortisol of 6.7 mcg/dl (8-19 mcg/dl), UFC 76 mcg/dl (6-42 mcg/dl) and normal late night salivary cortisol 0. 071, 0. 067 mcg/dl (<0. 010-0. 090 mcg/dl). Her repeat CT abdomen showed bilateral adrenal nodules with larger nodule on the left side measuring 2.4 cm. She underwent adrenal vein sampling using epinephrine as control which showed bilateral cortisol secretion. She did not tolerate medical therapy with Mifepristone. Testing for aberrant receptors was negative. She eventually underwent left adrenalectomy which improved her clinical co-morbidities and normalized cortisol levels. Her postoperative DST cortisol is 1.5 mcg/dl (8-19 mcg/dl) and UFC is 8 mcg/24hr (6-42 mcg/24hr). Her genetic testing is still pending.

Discussion

The conventional treatment of PBMAH is adrenalectomy. Unilateral adrenalectomy of larger adrenal gland is now considered a reasonable alternative to bilateral adrenalectomy in selected patients due to risk of adrenal insufficiency and lifetime steroid dependency with bilateral surgery (1). Cortisol secretion in PBMAH can be regulated by aberrant adrenal expression of receptors and all patients should be evaluated for these receptors as there is potential for medical therapy in them. PMBAH is also caused by ARMC5 mutations in familial cases, and it is commonly associated with intracranial meningiomas suggesting a possibility of new syndrome which needs to be further studied. Cranial imaging should be offered to these patients to exclude a coexisting meningioma (2). References: 1. Unilateral Adrenalectomy as a First-Line Treatment of Cushing's Syndrome in Patients With Primary Bilateral Macronodular Adrenal Hyperplasia. J Clin Endocrinol Metab. 2015 Dec;100(12): 4417-24. 2. Molecular and clinical evidence for an ARMC5 tumor syndrome: concurrent inactivating germline and somatic mutations are associated with both primary macronodular adrenal hyperplasia and meningioma. J Clin Endocrinol Metab. 2015 Jan;100(1): E119-28-

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