Addressing the Clinical Conundrum of Localization in ACTH-independent Cushing Syndrome With Bilateral Adrenal Nodules

ACTH-independent Cushing syndrome is commonly caused by a unilateral adrenal adenoma. However, in cases with bilateral adrenal nodules, localization of the functional lesion is challenging. We present the case of a 26-year-old woman with ACTH-independent Cushing syndrome and concurrent bilateral adrenal nodules. Using dexamethasone-suppressed adrenal venous sampling (AVS), an adrenal vein to peripheral vein cortisol ratio >6.5, and an aldosterone-corrected cortisol lateralization ratio >2.3, the autonomous cortisol secretion was localized to the right adrenal adenoma. She underwent a right posterior retroperitoneal laparoscopic adrenalectomy resulting in clinical and biochemical resolution of hypercortisolism. Postoperatively, she required hydrocortisone therapy, which was successfully discontinued after 4 years. The use of dexamethasone-suppressed AVS, in conjunction with aldosterone-corrected cortisol lateralization ratio, may enhance the diagnostic accuracy of AVS.