What is the initial approach to managing an adrenal adenoma?

Initial Approach to Managing an Adrenal Adenoma

The initial approach to managing an adrenal incidentaloma requires comprehensive assessment of hormonal function and oncologic risk through radiological evaluation, hormonal testing, and risk stratification to determine appropriate treatment or surveillance. 1

Initial Evaluation

Radiological Assessment

• Unenhanced CT scan is the first-line imaging modality to determine if the mass is benign or malignant 1
• Benign features include:
  • Low attenuation (≤10 Hounsfield Units) suggesting fat-containing adenoma 1
  • Homogeneous appearance 2
  • Size <4 cm 1
• Malignant features include:
  • Size >4 cm (higher risk) 1
  • Heterogeneous appearance 2
  • Hounsfield Units >20 2

Hormonal Evaluation

All patients with adrenal incidentalomas should undergo:

• 1-mg overnight dexamethasone suppression test (using cortisol cutoff ≤50 nmol/L or ≤1.8 μg/dL) to exclude cortisol excess 2, 3
• Measurement of plasma or urinary metanephrines to exclude pheochromocytoma 4, 2
• Aldosterone-to-renin ratio in patients with hypertension or unexplained hypokalemia to screen for primary aldosteronism 1
• If adrenocortical carcinoma is suspected based on imaging, additional testing for sex hormones and steroid precursors 1

Management Algorithm

For Non-functioning Adenomas with Benign Features

• Size <4 cm with benign radiological features (≤10 HU):
  • No further follow-up imaging or functional testing required 1
• Size ≥4 cm with benign radiological features:
  • Repeat imaging in 6-12 months 1
  • If growth <3 mm/year: no further imaging or testing required 1
  • If growth >5 mm/year: repeat functional work-up and consider adrenalectomy 1

For Indeterminate Non-functioning Lesions

• Options include:
  • Repeat imaging in 3-6 months 1
  • Immediate surgical resection if high suspicion for malignancy 1
  • Decision should be based on patient preference and overall health 1

For Functioning Adenomas

• Aldosterone-secreting adenomas:
  • Adrenalectomy is recommended 1
  • Minimally invasive surgery when feasible 1
• Cortisol-secreting adenomas:
  • Adrenalectomy should be considered in patients with "autonomous cortisol secretion" and related comorbidities (hypertension, diabetes) 2, 3
• Pheochromocytomas:
  • Surgical resection is the treatment of choice 4
  • Preoperative alpha-blockade is essential 4

For Suspected Malignancy

• Adrenocortical carcinoma:
  • Surgical resection is recommended 1
  • Open approach preferred for masses >6 cm or with invasive features 1
  • Complete surgical extirpation (R0 resection) is the mainstay of potentially curative approaches 1

Follow-up Recommendations

For Non-operated Benign, Non-functioning Adenomas

• <4 cm with benign features: no further follow-up required 1
• ≥4 cm with benign features: repeat imaging in 6-12 months 1

For Operated Patients

• For aldosterone-secreting adenomas: post-operative hormonal work-up only in short-term to confirm resolution of hyperfunction 1
• For pheochromocytomas: biochemical tests approximately 14 days after surgery to verify absence of residual disease 4

Common Pitfalls and Caveats

• Adrenal incidentalomas are common (prevalence ~4% in adults, ~10% in individuals over 70 years) 1
• Most adrenal incidentalomas (~75%) are benign non-functional adenomas, but ~20% require surgical intervention 1
• Bilateral adrenal incidentalomas should be evaluated individually using the same protocol 1
• Adrenal biopsy is rarely indicated and potentially harmful for resectable primary adrenal tumors 1
• Mild autonomous cortisol secretion (MACS) is associated with increased morbidity and mortality even without overt Cushing's syndrome 2
• Young patients, pregnant women, and children with adrenal masses require expedited evaluation due to higher risk of malignancy 1