What is the initial approach to treating an adrenal adenoma?

Initial Approach to Treating an Adrenal Adenoma

The initial approach to treating an adrenal adenoma requires a focused evaluation of hormonal function and malignancy risk, with treatment decisions based primarily on these findings rather than size alone. 1

Initial Evaluation

Imaging Assessment

• Non-contrast CT is the first-line imaging to distinguish benign from suspicious lesions 1
  • Lesions with <10 Hounsfield Units (HU) are considered benign 1
  • For indeterminate lesions on non-contrast CT, proceed to second-line imaging:
    • CT with washout protocol (benign if >60% washout at 15 minutes) 1
    • Chemical-shift MRI 1

Hormonal Evaluation

All patients with adrenal adenomas must undergo:

1. 1-mg overnight dexamethasone suppression test (cortisol ≤50 nmol/L or ≤1.8 μg/dL excludes autonomous cortisol secretion) 1
2. Plasma or 24-hour urinary metanephrines (to exclude pheochromocytoma) 1
3. Aldosterone-to-renin ratio (only if hypertension or hypokalemia present) 1
4. Androgen testing (only if suspected adrenocortical carcinoma or clinical signs of virilization) 1

Treatment Algorithm Based on Evaluation Results

1. Functioning Adenomas

• Cortisol-secreting adenomas:

  • With overt Cushing's syndrome: Unilateral adrenalectomy 1
  • With mild autonomous cortisol secretion (MACS): Consider adrenalectomy in younger patients with progressive metabolic comorbidities 1

• Aldosterone-secreting adenomas:

  • Adrenal vein sampling recommended before surgery to confirm unilateral source 1
  • Treatment options:
    • Unilateral adrenalectomy (preferably minimally invasive) 1
    • Medical management with spironolactone (100-400 mg daily) for poor surgical candidates 2

• Pheochromocytomas:

  • Always require surgical resection 1
  • Preoperative alpha-blocker therapy for 1-3 weeks before surgery 1

2. Non-functioning Adenomas

• Benign appearance (<10 HU) and <4 cm:

  • No further follow-up imaging or functional testing required 1

• Benign appearance (<10 HU) but ≥4 cm:

  • Repeat imaging in 6-12 months 1
  • If growth >5 mm/year: Consider adrenalectomy after repeating functional workup 1
  • If growth <3 mm/year: No further imaging or testing needed 1

• Indeterminate or suspicious for malignancy:

  • Lesions >4 cm with inhomogeneous appearance or HU >20: Surgical resection 3
  • Smaller indeterminate lesions: Repeat imaging in 3-6 months or consider surgical resection based on shared decision-making 1

Surgical Approach Considerations

• Minimally invasive surgery (laparoscopic/robotic) is preferred for:

  • Benign-appearing, functioning adenomas 1
  • Small (<6 cm) suspected adrenocortical carcinomas that can be safely resected without rupturing the capsule 1

• Open adrenalectomy should be considered for:

  • Larger adrenocortical carcinomas
  • Locally advanced tumors
  • Presence of lymph node metastases or tumor thrombus 1

Important Clinical Pitfalls

1. Never perform routine adrenal mass biopsy for the workup of an adrenal incidentaloma 1
2. Don't rely solely on size for determining malignancy risk; imaging characteristics are more reliable 1
3. Don't miss subclinical hormone production which can lead to significant morbidity even without overt clinical syndrome 3
4. Consider multidisciplinary review when imaging is not consistent with benign lesion, there is evidence of hormone hypersecretion, significant tumor growth, or when surgery is being considered 1
5. Special consideration for bilateral adenomas: Evaluate each lesion separately and consider measuring 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia 1

By following this structured approach, clinicians can effectively determine which adrenal adenomas require surgical intervention versus observation, ultimately reducing unnecessary procedures while ensuring appropriate treatment for functioning or potentially malignant lesions.