What is the management approach for a patient with a 1.6 cm left adrenal nodule consistent with an adenoma, without symptoms or biochemical evidence of hormonal excess?

Management of 1.6 cm Left Adrenal Adenoma

For a 1.6 cm adrenal nodule consistent with an adenoma, you must first complete hormonal screening to exclude autonomous cortisol secretion, pheochromocytoma (if indicated), and primary aldosteronism (if hypertensive), then proceed with imaging surveillance at 12 months followed by annual clinical follow-up for 4 years if all hormonal testing is normal. 1, 2

Mandatory Initial Hormonal Screening

Even though the imaging characteristics suggest a benign adenoma, all patients with adrenal incidentalomas ≥1 cm must undergo complete functional testing regardless of imaging appearance or symptoms. 2

Required Tests for All Patients:

• 1 mg overnight dexamethasone suppression test to screen for autonomous cortisol secretion, which occurs in 5.3% of incidentalomas even when appearing benign 1, 2
• Cortisol >138 nmol/L (>5.0 µg/dL) after dexamethasone indicates autonomous secretion 1

Additional Testing Based on Clinical Features:

• Plasma aldosterone-to-renin ratio if the patient has hypertension and/or hypokalemia, with ratio >20 ng/dL per ng/mL/hr indicating primary aldosteronism 2
• Plasma free metanephrines or 24-hour urinary fractionated metanephrines only if the mass measures ≥10 Hounsfield Units on non-contrast CT or if symptoms of catecholamine excess are present 2

Critical Pitfall to Avoid:

Never skip the dexamethasone suppression test even in small, benign-appearing masses, as autonomous cortisol secretion is present in 5.3% of incidentalomas and is associated with increased cardiovascular morbidity and metabolic abnormalities. 1, 2, 3

Imaging Surveillance Protocol

Since this is a 1.6 cm adenoma (below the 4 cm threshold), the following surveillance applies:

For Benign-Appearing Adenomas <4 cm with Normal Hormonal Workup:

• Reimage at 12 months from initial diagnosis 2
• Annual clinical follow-up for 4 years total 2
• No further imaging or functional testing required if the mass grows <3 mm/year 1

If Growth Occurs During Surveillance:

• Repeat complete functional workup if growth is >5 mm/year 1, 2
• Consider adrenalectomy if growth exceeds 5 mm/year after repeating hormonal evaluation 1

When Surgery Is NOT Indicated

Patients with benign non-functional adenomas <4 cm do not require adrenalectomy and do not need further follow-up imaging or functional testing after the initial 4-year surveillance period. 1

Multidisciplinary Review Threshold

Obtain consultation with endocrinology, surgery, and radiology if any of the following develop: 1

• Evidence of hormone hypersecretion on initial or follow-up testing
• Tumor growth >5 mm/year during surveillance
• Imaging characteristics become indeterminate or concerning
• Patient develops new symptoms suggestive of hormonal excess

Hormonal Surveillance Controversy

There is divergence in guidelines regarding repeat hormonal testing:

• The Endocrine Society does not recommend repeat hormonal testing if initial values were normal 2
• However, other guidelines (AACE/AAES and CUA) recommend annual hormonal panels for 5 years after diagnosis 2

Given the low cost and potential benefit of detecting developing autonomous cortisol secretion, consider annual dexamethasone suppression testing for 4 years during the surveillance period, particularly in patients developing new hypertension, diabetes, or weight gain. 2, 3