SUN-178 Clinical and Anatomopathological Characteristics of Two Atypical Aldosterone-Producing Adenomas

Background: Aldosterone producing adenomas (APAs) are the most common cause of unilateral primary aldosteronism (PA). In most cases, APAs present as small (<2 cm in diameter) benign appearing nodules on computed tomography (CT). Up to 70% of APAs may harbor KCNJ5 somatic mutations. Clinical Cases: Case 1. A 33-yr-old man was referred to investigate resistant hypertension (HT). Biochemical evaluation revealed normal K levels, aldosterone (A) of 14.7 ng/dl, renin of 2.1 mUI/L (normal, 4.4-46.1) and A/R ratio of 24.8. Confirmatory testing confirmed PA diagnosis. Hypercortisolism investigation revealed a non-suppressible cortisol after an overnight 1 mg low-dose dexamethasone suppression (8.3 μg/dL), abnormal midnight salivary cortisol, and normal urinary free cortisol, plasma DHEAS and ACTH levels. Computed tomography (CT) scan showed a well-limited mass in left adrenal, measuring 5.8 cm with pre-contrast density of 30 HU and absolute wash-out of 72%. After left laparoscopic adrenalectomy, hydrocortisone was started and adrenal insufficiency confirmed by basal cortisol <3 μg/dL. He presented biochemical cure of PA and improvement in HT control. Histologic examination revealed an encapsulated tumor with glomerulosa-like cells predominance and a Weiss score 1 (clear cells <25%). CYP11B2 staining was positive in 10% and Ki67 in 5% of tumor cells. Case 2. A 58 yr-old woman was referred to investigate an adrenal mass. She had resistant HT and hypokalemia since 2010. Biochemical evaluation revealed hypokalemia (2.8 mEq/L), A of 16.9 ng/dl, renin <1.6 mUI/L and A/R ratio of 10.6. Confirmatory testing confirmed PA diagnosis. Hypercortisolism investigation was negative. CT scan showed a heterogeneous solid mass in the right adrenal, measuring 5.5 cm with pre-contrast density of 30 HU and absolute wash-out of 77%. After laparoscopic right adrenalectomy, histologic examination revealed an encapsulated tumor with glomerulosa-like cells predominance and a Weiss score 2 (clear cells < 25% and > 1/3 diffuse architecture). CYP11B2 staining was positive in 30% and Ki67 in 5% of the cells. She presented biochemical cure of PA and improvement in HT control. Genetic investigation for somatic KCNJ5, ATP1A1, ATP2B3 and CTNNB1 was negative in both cases. Conclusion: We describe two rare cases of APAs that presented as large and suspicious tumors, without somatic mutations in genes associated with APAs.