European Society of Endocrinology clinical practice guidelines on the management of adrenal incidentalomas, in collaboration with the European Network for the Study of Adrenal Tumors

Each adrenal mass requires dedicated adrenal imaging. Homogeneous lesions with Hounsfield unit (HU) ≤ 10 on unenhanced CT are benign and need no additional imaging independent of size. All others should be discussed in a multidisciplinary expert meeting; only lesions >4 cm that are inhomogeneous or have HU >20 have risk of malignancy high enough that surgery is usually the management of choice.

Every patient needs clinical and endocrine work-up to exclude hormone excess, incl. plasma or urinary metanephrines and a 1-mg overnight dexamethasone suppression test (cutoff serum cortisol ≤50 nmol/L [≤1.8 µg/dL]); post-dexamethasone cortisol >50 nmol/L (>1.8 µg/dL) without overt CS is termed mild autonomous cortisol secretion (MACS).

All patients with MACS should be screened for comorbidities potentially attributable to cortisol (eg, hypertension, T2D) to ensure appropriate treatment.

In patients with MACS and relevant comorbidities, surgical treatment should be considered in an individualized approach.

Appropriateness of surgery should be guided by likelihood of malignancy, presence and degree of hormone excess, age, general health and patient preference.

Surgery is not usually indicated for an asymptomatic, nonfunctioning unilateral adrenal mass with obvious benign features on imaging.