6375 The Dilemma Of Bilateral Adrenal Tumors: A Case Of Pheochromocytoma With Contralateral Primary Aldosteronism

Abstract Disclosure: D. Caesario: None. K.L. Hermayer: None. Introduction: Adrenal tumors (ATs), once discovered, will need to be evaluated for malignancy and autonomous hormone secretion (AHS). Up to 90% of ATs are benign, but may still have AHS, with cortisol being the most common, found in up to 30% of cases. Only 5% of ATs are pheochromocytomas (PCCs) and 2% are primary aldosteronisms (PAs). ATs of different nature may simultaneously be present in the same patient, albeit very rare. We present a case of bilateral ATs confirmed to be PCC on one side, with subsequent development of PA contralaterally. CASE REPORT: A 67-year-old male with history of hypertension (HTN) had microscopic hematuria on routine urinalysis. He was otherwise asymptomatic. HTN was controlled with amlodipine (AMLO) and carvedilol (CVDL), and physical exam was normal. CT scan revealed 3 cm right kidney mass concerning for renal cell carcinoma (RCC). It also incidentally revealed 3.6 cm right AT with unenhanced Hounsfield Unit (uHU) of 23.9 and 9 mm left AT with uHU of -6.4. Labs revealed significantly elevated plasma fractionated metanephrines (MN) and urine catecholamines, highly suspicious for PCC. BMP, dexamethasone suppression test (DST), DHEA-S, renin, and aldosterone were normal. He underwent right nephrectomy and adrenalectomy. Pathology confirmed the diagnoses of RCC and PCC. PASS score <4. Genetic test was negative for PCC-related mutations. Subsequent annual surveillance revealed normal MN and negative DST. Imaging showed left AT with stable size and characteristics, and no signs of recurrent PCC. However, patient developed hypokalemia (hypoK) 3 years later that persisted despite potassium supplementation. His HTN became uncontrolled despite taking AMLO, CVDL, lisinopril, and hydrochlorothiazide. Repeat labs revealed renin <0.04 and aldosterone 12 in the setting of hypoK. Patient was then diagnosed with PA. He was initially started on amiloride, which led to the improvement in HTN and hypoK, with the plan to switch to spironolactone. DISCUSSION: PCCs have highly variable clinical manifestations. The classic clinical triad of headache, palpitations, and diaphoresis is not present in most patients and can rarely be totally asymptomatic. PA presents with HTN, and hypoK was previously considered to be essential for its diagnosis. However, recent evidence shows that only 9-37% of patients with PA have hypoK. The case above is unique, in that patient presented with multiple rare findings. He had bilateral ATs of different nature, was asymptomatic for his PCC, and his PA presented with hypoK, which was only clinically apparent 3 years after the initial adrenalectomy for his PCC. All published guidelines agree that patients with hormonally active or malignant unilateral ATs are candidates for surgical interventions, but the risks associated with bilateral adrenalectomy outweighed the potential benefits in his case. Fortunately, he responded well to the medical therapy for PA. Presentation: 6/2/2024