What is the recommended approach to evaluate an adrenal adenoma in a typical adult patient?

How to Evaluate an Adrenal Adenoma

All patients with an adrenal mass ≥1 cm require both comprehensive hormonal screening and radiological characterization, regardless of imaging appearance or symptoms. 1, 2

Initial Radiological Characterization

Obtain non-contrast CT as the first-line imaging study to distinguish benign from potentially malignant lesions. 1, 2, 3

• Masses measuring <10 Hounsfield Units (HU) are lipid-rich benign adenomas that require no further imaging characterization (100% specificity for benign disease). 1, 2, 3
• Masses measuring >10 HU require additional characterization with either contrast-enhanced CT with washout protocol or chemical-shift MRI. 1, 2
• For indeterminate masses on CT, adenomas demonstrate >60% absolute washout or >40% relative washout at 15 minutes after contrast administration. 2
• Masses >4 cm with irregular margins, heterogeneity, or HU >20 raise concern for adrenocortical carcinoma and warrant surgical evaluation. 1

Mandatory Hormonal Screening for All Patients

Screen Every Patient for Autonomous Cortisol Secretion

Perform a 1 mg overnight dexamethasone suppression test in all patients, as autonomous cortisol secretion occurs in 5-30% of incidentalomas and increases cardiovascular morbidity. 2, 4, 3, 5

• Cortisol ≤50 nmol/L (1.8 μg/dL) excludes hypersecretion 2, 4, 3
• Cortisol 51-138 nmol/L (1.9-5.0 μg/dL) suggests possible autonomous secretion 2, 4, 3
• Cortisol >138 nmol/L (>5.0 μg/dL) confirms autonomous cortisol secretion 2, 4, 3

Screen Selectively for Pheochromocytoma

Measure plasma free metanephrines or 24-hour urinary metanephrines/normetanephrines if:

• The mass measures ≥10 HU on non-contrast CT, OR 2, 4, 3
• The patient has symptoms of catecholamine excess (episodic hypertension, headache, palpitations, diaphoresis) 2, 4, 3

Do not screen for pheochromocytoma in lipid-rich adenomas (<10 HU) without symptoms, as the risk is negligible in this population. 3

Screen Selectively for Primary Aldosteronism

Measure plasma aldosterone-to-renin ratio only in patients with:

• Hypertension and/or hypokalemia 2, 4, 3
• A ratio >20 ng/dL per ng/mL/hr has excellent sensitivity and specificity for hyperaldosteronism 2, 4

Focused Clinical Assessment

Look for Signs of Cortisol Excess

• Weight gain, central obesity, moon facies, buffalo hump 3
• Purple striae, easy bruising, proximal muscle weakness 3
• Hypertension, diabetes, osteoporosis 3

Look for Signs of Aldosterone Excess

• Resistant hypertension, hypokalemia 3
• Muscle weakness and cramping 3

Look for Signs of Catecholamine Excess

• Episodic hypertension, headache, palpitations, diaphoresis 2

Critical Management Decisions

When to Pursue Surgery

Recommend adrenalectomy for:

• Masses >4 cm (higher malignancy risk, especially if >5 cm) 1
• Any hormonally active mass causing clinical symptoms 1
• Imaging characteristics suspicious for malignancy (irregular margins, heterogeneity, HU >20, poor washout) 1
• Growth >5 mm per year on surveillance imaging 4

Use open adrenalectomy (not laparoscopic) for masses with high malignancy risk to reduce peritoneal spread and local recurrence. 1

When to Pursue Surveillance

For benign-appearing adenomas <4 cm with <10 HU and normal hormonal workup:

• Reimage at 12 months, then annually for 4 years 4
• No need to repeat hormonal testing if initially normal per Endocrine Society, though some guidelines recommend annual hormonal panels for 5 years 4

For benign-appearing adenomas 4-6 cm:

• Reimage at 3-6 months, then at 6-12 month intervals for 1-2 years 4
• Consider adrenalectomy if mass enlarges by >1 cm in 1 year 4

Critical Pitfalls to Avoid

Never perform adrenal biopsy routinely for workup of an incidentaloma—only consider when diagnosis of metastatic disease from an extra-adrenal malignancy would change management. 4, 3 Always rule out pheochromocytoma before any biopsy to avoid precipitating a hypertensive crisis. 4, 3

Never skip dexamethasone suppression testing, even in small, benign-appearing masses, as autonomous cortisol secretion occurs in 5.3% of all incidentalomas. 4, 3

Do not rely solely on CT imaging to distinguish unilateral aldosterone-producing adenoma from bilateral hyperplasia—adrenal vein sampling is the gold standard when surgical intervention is considered. 4

Multidisciplinary Review Triggers

Obtain multidisciplinary review by endocrinology, surgery, and radiology when:

• Imaging is not consistent with a benign lesion 1
• Evidence of hormone hypersecretion exists 1
• The tumor has grown significantly during follow-up 1
• Adrenal surgery is being considered 1