What is the management approach for a benign left adrenal adenoma?

Management of Benign Left Adrenal Adenoma

Benign adrenal adenomas that are non-functioning and less than 4 cm with definitive benign imaging characteristics (homogeneous lesions with Hounsfield units ≤10 on unenhanced CT) do not require further imaging follow-up or surgical intervention. 1

Diagnostic Evaluation

Imaging Assessment

• Initial evaluation requires dedicated adrenal imaging:
  • Non-contrast CT: HU <10 indicates benign adenoma with 0% risk of adrenocortical carcinoma 1
  • For indeterminate lesions:
    • Contrast-enhanced washout CT: >60% washout at 15 minutes suggests benign lesion 1
    • Chemical-shift MRI: Signal intensity loss in opposed-phase images indicates benign adenoma 1

Hormonal Evaluation

All patients with adrenal adenomas should undergo complete hormonal evaluation regardless of symptoms:

1. 1-mg overnight dexamethasone suppression test (cortisol ≤50 nmol/L or ≤1.8 µg/dL indicates normal suppression) 1, 2
2. Plasma or 24-hour urinary metanephrines for pheochromocytoma 1, 2
3. Aldosterone-to-renin ratio if hypertensive to screen for primary aldosteronism 1

Management Algorithm

For Non-functioning Adenomas:

1. Size <4 cm with definitive benign features (HU ≤10):

   • No further imaging or functional testing required 1
   • No surgical intervention needed 1, 2

2. Size <4 cm but indeterminate features (HU >10):

   • Repeat imaging in 3-6 months 1
   • If stable, annual imaging for 1-2 years 3
   • Consider surgery if growth >5 mm/year after repeating hormonal evaluation 1

3. Size ≥4 cm:

   • Consider surgical evaluation even if benign-appearing 1
   • Repeat imaging in 6-12 months if not surgically removed 1

For Functioning Adenomas:

• All functioning adenomas (cortisol, aldosterone, or catecholamine-producing) should be surgically removed regardless of size 1, 2
• For mild autonomous cortisol secretion (MACS):
  • Screen for cortisol-related comorbidities (hypertension, diabetes) 2
  • Consider surgery if significant comorbidities are present 2

Surgical Considerations

• Minimally invasive surgery (laparoscopic approach) is preferred for benign adenomas when technically feasible 1
• Perioperative steroid coverage is mandatory for cortisol-producing adenomas to prevent adrenal crisis 1
• Approximately 50% of patients experience temporary adrenal insufficiency after removal of cortisol-producing adenomas 1

Follow-up Recommendations

• Benign non-functioning adenomas <4 cm with definitive benign features require no follow-up 1
• Recent evidence suggests the risk of a benign, non-functional mass becoming malignant or hormonally active during follow-up is extremely low 4
• For indeterminate masses that are not surgically removed, follow-up should include:
  • Repeat imaging in 3-6 months, then annually for 1-2 years 1, 3
  • Annual hormonal evaluation for up to 5 years, especially for tumors >3 cm 3

Important Caveats

• Never assume an adrenal mass is non-functioning without complete hormonal evaluation, even in asymptomatic patients 1, 3
• Tumor density (HU value) is superior to tumor size in distinguishing benign from malignant adrenal masses 4
• Suspicious features warranting surgical consideration include:
  • Size >4 cm
  • Irregular margins
  • Heterogeneous appearance
  • Poor contrast washout (<60% at 15 minutes)
  • Growth >5 mm/year
  • Any hormone production 1

The management approach has evolved in recent years, with evidence suggesting that routine long-term follow-up for clearly benign, non-functioning adenomas may be unnecessary, allowing for more individualized and cost-effective care 4.