What is the recommended follow-up for a 34mm adrenal adenoma?

Follow-up Management for a 34mm Adrenal Adenoma

For a 34mm adrenal adenoma, follow-up should include repeat imaging in 6-12 months to assess for growth, with no further imaging needed if stable and <4cm, while considering surgery if growth >5mm/year is observed. 1

Initial Evaluation

Before establishing a follow-up plan, proper characterization of the adrenal mass is essential:

1. Hormonal Assessment (mandatory for all adrenal masses):

   • 1mg overnight dexamethasone suppression test for cortisol assessment 1, 2
     • <50 nmol/L (<1.8 μg/dL): excludes autonomous cortisol secretion
     • 51-138 nmol/L (1.8-5.0 μg/dL): possible autonomous cortisol secretion

     • 138 nmol/L (>5.0 μg/dL): evidence of autonomous cortisol secretion

   • Plasma free metanephrines or 24-hour urinary metanephrines (especially for nodules with HU >10) 1
   • Aldosterone-to-renin ratio if hypertension/hypokalemia present 1

2. Imaging Characterization:

   • Non-contrast CT: HU <10 indicates benign adenoma 1, 3
   • Contrast-enhanced CT: >60% washout at 15 minutes suggests benign lesion 1
   • Chemical-shift MRI: Signal intensity loss in opposed-phase images indicates benign adenoma 1

Follow-up Protocol for 34mm Adrenal Adenoma

Imaging Follow-up:

• First follow-up imaging: Repeat CT or MRI in 6-12 months to assess for growth 1, 4
• Subsequent follow-up:
  • If stable and <4cm: No further imaging needed 1
  • If growth >5mm/year: Consider surgical removal 1, 5

Hormonal Follow-up:

• Annual hormonal assessment for non-functioning adenomas 4
• More frequent monitoring if borderline hormonal values are detected 4
• Pay special attention to development of Mild Autonomous Cortisol Secretion (MACS), which can contribute to metabolic comorbidities without overt Cushing's syndrome 1, 2

Indications for Surgical Intervention

Consider surgery if any of the following develop during follow-up:

• Significant growth (>5mm/year) 1, 5
• Development of hormonal hypersecretion 1, 2, 6
• Development of symptoms related to mass effect 1
• Imaging features concerning for malignancy 1, 3

Risk Assessment During Follow-up

The cumulative risk of developing endocrine abnormalities increases over time:

• 17% at 1 year
• 29% at 2 years
• 47% at 5 years 5

The risk of mass enlargement also increases with time:

• 6% at 1 year
• 14% at 2 years
• 29% at 5 years 5

Common Pitfalls to Avoid

1. Not performing complete hormonal evaluation: Even classic-appearing adenomas can be hormonally active 1
2. Overlooking subtle hormonal changes: MACS can contribute to metabolic comorbidities without overt Cushing's syndrome 1, 2
3. Inadequate imaging follow-up: Missing significant growth that would indicate need for surgery 1, 5
4. Failure to recognize pheochromocytoma: Can lead to dangerous intraoperative hypertensive crisis if surgery is planned 1

Special Considerations

• Multidisciplinary approach: Management should involve collaboration between radiologists, endocrinologists, and surgeons, especially if imaging is not consistent with a benign lesion or if there is evidence of hormone hypersecretion 1
• Patient age and comorbidities: These factors should be considered when determining the intensity of follow-up and surgical decisions 6, 4