In a young woman with an incidentally discovered 1 cm adrenal mass on ultrasound, how should it be evaluated and managed?

Management of 1 cm Adrenal Mass in a Young Woman

A 1 cm adrenal mass discovered on ultrasound in a young woman requires both hormonal evaluation and dedicated imaging with non-contrast CT as the next step, even though lesions exactly 1 cm represent a threshold where some guidelines suggest observation alone. 1

Initial Imaging Approach

The ultrasound finding needs confirmation and characterization with non-contrast CT (NCCT) as the first-line dedicated imaging study 1. This is critical because:

• Ultrasound cannot adequately characterize adrenal masses
• NCCT measures Hounsfield Units (HU) to distinguish benign from indeterminate lesions
• Lesions measuring ≤10 HU on NCCT are benign lipid-rich adenomas requiring no further imaging 1, 2

Important Caveat for Young Women

While guidelines technically apply to lesions >1 cm, adrenal masses in young adults warrant more aggressive evaluation because they are statistically more likely to be malignant compared to older adults 2, 3. The typical 4% prevalence in adults increases to 10% in those over 70, meaning younger patients have proportionally higher malignancy risk when masses are present.

Mandatory Hormonal Evaluation

All patients with adrenal incidentalomas ≥1 cm must undergo comprehensive biochemical screening, regardless of symptoms 2:

Required Tests for Everyone:

• 1 mg overnight dexamethasone suppression test (preferred screening for autonomous cortisol secretion) 2
• Plasma free metanephrines or 24-hour urinary metanephrines (to exclude pheochromocytoma) 2

Additional Tests if Hypertensive or Hypokalemic:

• Aldosterone-to-renin ratio (screening for primary aldosteronism) 2
• Serum potassium 4

If Virilization Signs Present:

• Serum androgen testing 2

Management Algorithm Based on NCCT Results

If NCCT shows ≤10 HU (Benign Adenoma):

• No further imaging required 1, 2
• No follow-up needed if <4 cm and non-functional 2
• Exception: Screen for pheochromocytoma can be omitted if clearly <10 HU AND no adrenergic symptoms 2

If NCCT shows 11-20 HU:

According to the most recent 2025 ESE guidelines 1:

• Immediate additional imaging with either:
  • Adrenal protocol CT with washout
  • MRI with chemical shift imaging (CSI)
  • PET-CT
• Alternative approach: Follow-up imaging at 12 months (acceptable option) 1
• MRI may be increasingly preferred given concerns about CT washout false positives/negatives 1

Critical Pitfall: Approximately 1/3 of adenomas don't washout in the typical adenoma range, and 1/3 of pheochromocytomas can mimic adenoma washout patterns 2. This is why hormonal testing cannot be skipped.

If NCCT shows >20 HU or Heterogeneous Appearance:

• Relevant risk of malignancy 1
• Multidisciplinary conference discussion required 1
• Consider surgical resection vs. follow-up at 6-12 months 1

Special Considerations for Young Women

1. Radiation safety is paramount - consider low-dose CT or MRI as first-line rather than standard CT 2
2. Lower threshold for surgical intervention given higher relative malignancy risk in younger patients 2, 3
3. Pregnancy considerations - if pregnant or planning pregnancy, MRI is strongly preferred over CT 2

When Surgery is Indicated

Immediate adrenalectomy (minimally invasive when feasible) is required for: 2, 5

• Any hormonally active tumor (pheochromocytoma, aldosteronoma, cortisol-secreting with overt Cushing's)
• Masses >4-6 cm without clear benign features
• Growth >5 mm/year on follow-up 2
• Suspected adrenocortical carcinoma

What NOT to Do

• Do not perform biopsy - rarely indicated and potentially dangerous, especially if pheochromocytoma not excluded 2
• Do not skip hormonal evaluation even if imaging suggests benign adenoma, unless clearly <10 HU 2
• Do not rely on ultrasound characteristics alone for management decisions 1

Bottom Line for This Case

For this 1 cm mass in a young woman: Obtain non-contrast CT immediately along with complete hormonal evaluation (dexamethasone suppression test and metanephrines at minimum). If NCCT shows ≤10 HU and hormones are normal, no further action needed. If NCCT shows >10 HU or any hormonal abnormality, proceed with additional imaging or surgery based on the algorithm above, with lower threshold for intervention given her young age.