Management Approach of Adrenal Incidentaloma

Abstract

Background:

The prevalence of adrenal incidentalomas is increasing substantially with cross-sectional imaging, with reported prevalence from 1% to 5% on computed tomography and up to 8.7% at autopsy. While the majority of incidentalomas are benign nonfunctional adenomas, clinicians face the critical challenge of identifying the rare adrenocortical carcinoma (0.5–2 per million annually), which carries an extremely poor prognosis with 5-year survival of only 50% and <15% if metastatic. Functioning adrenal tumors occur in 27.5% of incidentalomas, including mild autonomous cortisol secretion (MACS) in 5%–30%, primary aldosteronism in 5%–6%, and pheochromocytomas in 4%–8%.

Methods:

Comprehensive literature review of current evidence on adrenal incidentaloma management incorporating a systematic three-pillar diagnostic framework is presented: (1) imaging assessment based on Hounsfield unit attenuation and contrast washout, (2) comprehensive hormonal testing for cortisol excess, aldosterone excess, and pheochromocytoma, and (3) growth assessment over time.

Results:

A three-pillar diagnostic approach effectively stratifies adrenal incidentaloma management. Imaging: lesions with Hounsfield units <10 are benign (0% malignancy risk), 10–20 are indeterminate (0.5% risk), and >20 are suspicious (6.3% risk), both warranting comprehensive evaluation. Hormonal evaluation: MACS is diagnosed by a positive 1-mg dexamethasone suppression test for cortisol without clinical Cushing features; overt Cushing presents with markedly elevated cortisol, suppressed ACTH, and characteristic clinical stigmata. Primary aldosteronism with an aldosterone-to-renin ratio of >30 requires confirmatory testing. Pheochromocytoma diagnosis requires plasma-free metanephrines. A growth rate of >0.8 cm/year predicts malignancy.

Conclusions:

Comprehensive evaluation incorporating imaging characterization, hormonal testing, and growth surveillance provides an evidence-based framework for safe management of adrenal incidentalomas. Recent randomized controlled trials support expanded surgical indications in carefully selected MACS patients, particularly those with documented comorbidities, demonstrating superior cardiovascular and metabolic outcomes compared with medical management alone. The paradigm has shifted from treating secondary comorbidities medically to addressing the underlying autonomous cortisol production surgically. Minimally invasive adrenalectomy remains the gold standard surgical approach in experienced hands.