What is the appropriate management of adrenal incidentalomas?

Management of Adrenal Incidentalomas

Adrenal incidentalomas require endocrine evaluation in all cases, regardless of symptoms, to assess for subclinical hormone production and malignancy risk. 1 This evaluation is essential as these lesions are rarely malignant but may produce hormones that can impact patient health.

Characteristics of Adrenal Incidentalomas

• Most adrenal incidentalomas are benign, non-functioning adrenocortical adenomas
• Only a small percentage represent malignant lesions or hormone-producing tumors requiring intervention
• The prevalence of malignancy in adrenal incidentalomas is low, with primary adrenocortical carcinoma being rare 2

Initial Evaluation

Imaging Assessment

• All patients with adrenal incidentalomas should receive dedicated adrenal imaging 2
• Non-contrast CT is the preferred initial imaging modality
  • Homogeneous lesions with Hounsfield units (HU) ≤10 are benign regardless of size 1
  • Lesions with HU >10 require further evaluation
• Contrast-enhanced CT with washout studies can help characterize indeterminate lesions

  • 60% washout at 15 minutes suggests benign lesion 1

Hormonal Evaluation

Every patient with an adrenal incidentaloma requires comprehensive hormonal evaluation including 1, 2:

1. 1-mg overnight dexamethasone suppression test (DST)

   • Cutoff value: serum cortisol ≤50 nmol/L (≤1.8 μg/dL)
   • Values >50 nmol/L suggest mild autonomous cortisol secretion (MACS)

2. Plasma free metanephrines or 24-hour urinary fractionated metanephrines

   • To exclude pheochromocytoma
   • Values >2× upper limit of normal strongly suggest pheochromocytoma

3. Aldosterone-to-renin ratio (ARR)

   • For screening of primary hyperaldosteronism
   • Hyperaldosteronism is uncommon in adrenal incidentalomas 1

Management Approach

Surgical Indications

Surgery is recommended for 1, 2, 3:

• All masses >6 cm regardless of appearance
• Masses >4 cm with inhomogeneous appearance or HU >20
• Any biochemically confirmed hormone-producing tumor:
  • Pheochromocytomas
  • Aldosterone-secreting adenomas
  • Cortisol-secreting adenomas
• Lesions with growth >5 mm/year on follow-up imaging
• Patients with MACS who have relevant comorbidities (individualized approach)

Non-Surgical Management

For non-functioning adrenal masses with benign imaging characteristics:

• Masses <4 cm with HU ≤10 require no further follow-up imaging or functional testing 1
• Masses ≥4 cm but <6 cm with benign features should have repeat imaging in 6-12 months 1
• Patients with MACS should be screened and treated for potential cortisol-related comorbidities (hypertension, type 2 diabetes) 2

Follow-up Recommendations

• For non-operated patients with non-functioning masses:
  • Consider repeat screening for pheochromocytoma and hypercortisolism at 1-2 years 1
  • Benign-appearing adenomas (<4 cm) that remain unchanged do not require further follow-up 1
  • Repeat imaging if there are concerns about growth

Common Pitfalls to Avoid

1. Failing to perform hormonal evaluation - Even asymptomatic incidentalomas can produce subclinical hormone excess
2. Recommending surgery based on size alone - Consider both size and imaging characteristics
3. Overlooking pheochromocytoma - Always screen for catecholamine excess before considering biopsy or surgery
4. Excessive follow-up - Benign lesions with definitive imaging characteristics don't need prolonged surveillance

In summary, adrenal incidentalomas require a systematic approach to evaluation and management, with decisions based on imaging characteristics, hormonal status, and size. While most are benign and non-functioning, proper evaluation is essential to identify the minority that require intervention.