PS-R03-2: UNILATERAL PRIMARY ALDOSTERONISM AND CONTRALATERAL GROWING ADRENAL MASS: GROWING CONCERN FOR PHEOCHROMOCYTOMA

Abstract

Concomitant unilateral primary aldosteronism (PA) and pheochromocytoma is extremely rare. A 52-year-old previously healthy woman with no family history of endocrine disease was admitted to our hospital with suspected PA based on high blood pressure, spontaneous hypokalemia, and a high aldosterone-to-renin ratio. She had no catecholamine excess symptoms other than hypertension. Abdominal computed tomography (CT) showed a right lipid-rich adrenal mass and a left lipid-poor adrenal mass. PA was diagnosed by the captopril challenge test. The 24-h urinary fractionated metanephrines were slightly elevated. Adrenal vein sampling (AVS) confirmed that the right adrenal gland was responsible for aldosterone hypersecretion. Medical therapy with eplerenone was started because the patient refused surgery. Five years later, she requested surgery for PA. The second AVS confirmed right unilateral hyperaldosteronism, as expected. Repeat abdominal CT showed the enlargement of the left adrenal mass. The 24-h urinary fractionated metanephrines had risen to the diagnostic level. 123I-MIBG scintigraphy showed a marked accumulation in the left adrenal tumor with no metastatic lesion. After preoperative management of alpha-blockade, laparoscopic left partial adrenalectomy was performed. Immunohistochemical examination of the tumor showed chromogranin A positivity leading to the diagnosis of left pheochromocytoma. One year after surgery, blood pressure and serum K levels remain well controlled. No surgical treatment for the right adrenal mass has been performed, and PHEO has not recurred. This case highlights the potential pitfalls in the treatment and diagnosis of unilateral primary aldosteronism with contralateral pheochromocytoma. In cases of unilateral PA with contralateral lipid-poor adrenal mass, clinicians should rule out if the contralateral adrenal mass is pheochromocytoma to proceed to undergo unilateral adrenalectomy for the treatment of PA.