Mild Autonomous Cortisol Secretion in Congenital Adrenal Hyperplasia Managed With Mini Back Scope Adrenalectomy.

A 55-year-old woman, diagnosed with 21-hydroxylase deficiency congenital adrenal hyperplasia (CAH) at age 7 years in the mid-Atlantic United States and living mostly outside the country, recently developed mild autonomous cortisol secretion (MACS) with bilateral adrenal lesions. Initially managed with 20 years of glucocorticoid therapy for hyperandrogenism, she discontinued treatment at age 33 due to iatrogenic Cushing syndrome features, remaining off therapy for close to 20 years with stable eucortisolemia. Recent weight gain prompted evaluation, revealing elevated cortisol (3.1 µg/dL postdexamethasone suppression; SI: 86.1 nmol/L), undetectable ACTH, and a dominant right adrenal tumor (5.1 cm) but with bilateral lesions. She underwent right mini back scope adrenalectomy (MBSA). The pathology confirmed a benign adenoma, and postoperative hypercortisolemia resolved, with transient postoperative hypocortisolism managed with glucocorticoid replacement. This case highlights the rare emergence of MACS in people with longstanding CAH, underscoring the need for lifelong adrenal monitoring and the effectiveness of MBSA.