What is the management approach for an adrenal nodule identified on X-ray?

Management of Adrenal Nodules Identified on Imaging

For adrenal nodules identified incidentally on imaging, a comprehensive hormonal evaluation should be performed for all patients regardless of imaging appearance, followed by appropriate imaging characterization to determine malignancy risk, with surgical management recommended for nodules >4 cm that are inhomogeneous or have HU >20 on CT, or for hormone-producing tumors. 1

Initial Evaluation

Imaging Characterization

• First-line imaging: Non-contrast CT is the preferred initial imaging modality 1

  • Lesions with HU ≤10 are highly likely to be benign adenomas (risk of adrenocortical carcinoma 0%)
  • Homogeneous lesions with HU ≤10 do not require additional imaging regardless of size 2

• Second-line imaging (for indeterminate lesions):

  • Contrast-enhanced CT washout study (>60% washout at 15 minutes suggests benign lesion)
  • Chemical shift MRI (signal intensity loss in opposed-phase images indicates benign adenoma)
  • FDG-PET (useful for distinguishing potentially malignant lesions from benign tumors)

Hormonal Assessment

All patients with adrenal nodules require complete hormonal evaluation regardless of imaging appearance 1:

1. Cortisol assessment: 1mg overnight dexamethasone suppression test (cutoff value ≤50 nmol/L or ≤1.8 μg/dL)
2. Catecholamine assessment: Plasma-free or 24-hour urinary fractionated metanephrines
3. Aldosterone assessment: Aldosterone-to-renin ratio (if hypertension or hypokalemia present)

CAUTION: Always rule out pheochromocytoma before any invasive procedure to prevent life-threatening hypertensive crises 1

Management Algorithm

Surgical Management Indications

Surgery is recommended for:

1. Radiologically suspicious nodules:

   • Nodules >4 cm that are inhomogeneous or have HU >20 on CT 1, 2
   • Nodules with significant growth (>5 mm/year) on follow-up imaging 3

2. Hormone-producing tumors:

   • Pheochromocytomas (with preoperative alpha-blockade)
   • Aldosterone-secreting adenomas
   • Cortisol-secreting adenomas, especially with overt Cushing's syndrome or progressive metabolic comorbidities 1

Conservative Management

For benign-appearing, non-functioning adrenal nodules:

• Nodules <4 cm with benign radiological features (HU <10, homogeneous):

  • No further follow-up imaging or functional testing required 3

• Benign non-functional adenomas ≥4 cm:

  • Repeat imaging in 6-12 months 3
  • If growth <3 mm/year, no further imaging or functional testing required 3
  • If growth >5 mm/year, consider adrenalectomy after repeating functional work-up 3

• Indeterminate non-functioning lesions:

  • Shared decision-making between patient and clinician
  • Options include repeat imaging in 3-6 months or surgical resection 3

Special Considerations

Bilateral Adrenal Nodules

• Each lesion should be characterized separately
• Consider measuring serum 17-hydroxyprogesterone to exclude congenital adrenal hyperplasia
• Assess for adrenal insufficiency in suspected bilateral infiltrative disease, metastases, or hemorrhage 3

Indeterminate Lesions

• Multidisciplinary discussion involving endocrinologists, surgeons, and radiologists is recommended 1
• Biopsy is of limited value and should be avoided for suspected primary adrenal malignancy due to risk of dissemination 3, 1
• Consider patient comorbidities, compliance, and preference when deciding between repeat imaging and immediate surgery 3

IMPORTANT: The European Society of Endocrinology and American Urological Association both emphasize that even radiologically benign-appearing lesions can be hormonally active, so hormonal evaluation should never be skipped 1, 2

Follow-up Recommendations

• For non-functional benign lesions <4 cm: No further follow-up required 3
• For benign-appearing lesions ≥4 cm: Repeat imaging in 6-12 months 3
• For indeterminate lesions: Repeat imaging in 3-6 months 3
• For patients with mild autonomous cortisol secretion (MACS): Screen for and treat potential cortisol-related comorbidities 2