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 should be determined by its functional status and malignancy risk, with surgical resection indicated for all unilateral aldosterone-secreting adenomas, pheochromocytomas, cortisol-producing adenomas with overt Cushing's syndrome, and lesions with suspicious radiological features or size ≥4 cm with indeterminate imaging characteristics. 1, 2

Initial Evaluation

Imaging Assessment

• First-line imaging: Dedicated adrenal protocol CT with non-contrast phase
  • Benign adenoma: <10 Hounsfield Units (HU) on non-contrast CT
  • Indeterminate lesion: >10 HU requires contrast-enhanced CT with washout calculations

    • 60% washout at 15 minutes suggests benign adenoma

  • Chemical-shift MRI if CT is equivocal or contraindicated 2

Hormonal Evaluation

All adrenal adenomas require complete hormonal workup regardless of imaging characteristics:

• 1mg overnight dexamethasone suppression test (cortisol ≤50 nmol/L or ≤1.8 µg/dL indicates normal suppression)
• Plasma or 24-hour urinary metanephrines (pheochromocytoma screening)
• Aldosterone-to-renin ratio if hypertension or hypokalemia present 1, 2, 3

Management Algorithm Based on Adenoma Characteristics

Functional Adenomas

1. Aldosterone-producing adenomas:

   • Surgical resection (minimally invasive surgery when feasible)
   • Preoperative preparation not typically required
   • Post-operative hormonal work-up only needed short-term to confirm resolution 1

2. Pheochromocytomas:

   • Surgical resection (minimally invasive surgery when feasible)
   • Preoperative alpha-blocker therapy for 1-3 weeks
   • Beta-blockers can be added to control reflex tachycardia if needed 1

3. Cortisol-producing adenomas:

   • With overt Cushing's syndrome: Surgical resection
   • With mild autonomous cortisol secretion (MACS):
     • Screen for cortisol-related comorbidities (hypertension, diabetes)
     • Consider surgery in patients with progressive metabolic comorbidities
     • Annual clinical screening for patients not managed surgically 1, 3

Non-functional Adenomas

1. Benign-appearing adenomas <4 cm (radiologically benign with <10 HU):

   • No further imaging or functional testing required 1, 2

2. Non-functional adenomas ≥4 cm (radiologically benign with <10 HU):

   • Repeat imaging in 6-12 months
   • If growth >5 mm/year: Repeat functional work-up and consider adrenalectomy
   • If growth <3 mm/year: No further imaging or functional testing required 1

3. Indeterminate non-functional lesions:

   • Shared decision-making between patient and clinician
   • Options: Repeat imaging in 3-6 months or surgical resection 1, 2

Suspected Adrenocortical Carcinoma

• Surgical resection recommended
• For lesions >6 cm, open adrenalectomy may be preferred over laparoscopic approach due to concerns about peritoneal dissemination 1

Special Considerations

Bilateral Adrenal Adenomas

• Each lesion should be evaluated separately using the same criteria as unilateral nodules
• Consider measuring serum 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia 2

Primary Hyperaldosteronism Management

• For aldosterone-producing adenomas requiring long-term medical management:
  • Spironolactone 100-400 mg daily for patients unsuitable for surgery
  • Can be used as long-term maintenance therapy at lowest effective dosage 4

Follow-up After Resection

• For aldosterone-secreting adenomas: Post-operative hormonal work-up only needed short-term to confirm resolution
• Lack of biochemical cure should raise concern for bilateral disease, recurrence of aldosterone-secreting carcinoma (rare), or removal of non-hypersecreting adrenal gland 1

Pitfalls to Avoid

• Adrenal mass biopsy is rarely indicated and should not be routinely performed
• Never perform biopsy when pheochromocytoma has not been excluded (risk of hypertensive crisis)
• Avoid biopsy when adrenocortical carcinoma is suspected (risk of tumor seeding) 2
• Don't overlook the higher risk of malignancy in adrenal masses in younger patients 2
• Don't miss bilateral disease in primary hyperaldosteronism, which may require different management approaches 1

By following this structured approach to adrenal adenoma management, clinicians can ensure appropriate treatment decisions that prioritize patient morbidity, mortality, and quality of life outcomes.