What is the management approach for a 2 cm right adrenal adenoma?

Management of a 2 cm Right Adrenal Adenoma

For a 2 cm right adrenal adenoma, perform initial hormonal screening and obtain unenhanced CT to measure Hounsfield units; if the mass is non-functional with HU ≤10, no further follow-up imaging or hormonal testing is required. 1, 2

Initial Hormonal Evaluation

All patients with adrenal incidentalomas require comprehensive hormonal screening regardless of size or benign radiographic appearance, as approximately 5% harbor subclinical hormone production requiring treatment 2, 3:

• Perform 1 mg overnight dexamethasone suppression test to screen for autonomous cortisol secretion (cortisol >50 nmol/L or >1.8 µg/dL indicates mild autonomous cortisol secretion) 1, 4
• Measure plasma or 24-hour urinary metanephrines to exclude pheochromocytoma 1, 3
• Check aldosterone-to-renin ratio only if hypertension and/or hypokalemia present 1, 3

Imaging Characterization

Obtain unenhanced CT to measure Hounsfield units (HU) as the critical determinant of benign vs. indeterminate lesions 1:

• If HU ≤10: The mass is definitively a benign lipid-rich adenoma with 0% risk of malignancy 1, 4
• If HU >10: Perform second-line imaging with either washout CT or chemical-shift MRI to confirm benign characteristics 1, 2

Management Algorithm for Non-Functional Adenomas

If Non-Functional and HU ≤10:

No further follow-up imaging or functional testing is required 1, 2, 5. This recommendation is based on moderate-quality evidence showing 0% to <1% risk of malignant transformation in masses <3 cm with benign imaging characteristics 3.

If Functional Abnormalities Detected:

• Aldosterone-secreting adenoma: Perform adrenal vein sampling to lateralize production, then offer laparoscopic adrenalectomy 1, 2
• Pheochromocytoma: Adrenalectomy after appropriate alpha-blockade 2
• Mild autonomous cortisol secretion (MACS): Consider adrenalectomy only in younger patients with progressive metabolic comorbidities (hypertension, type 2 diabetes) attributable to cortisol excess after shared decision-making 1, 3, 4

Size-Specific Considerations

At 2 cm, this mass falls well below the 4 cm threshold where malignancy risk increases significantly 1. Most guidelines agree that masses <3-4 cm with benign imaging characteristics and no hormonal hypersecretion require no surveillance 2, 5.

Divergence in Guidelines

There is notable variation in follow-up recommendations among different societies 1:

• European Society of Endocrinology (ESE) and American College of Radiology (ACR): No follow-up imaging for benign, non-functional masses 1, 2
• American Association of Clinical Endocrinologists (AACE): Reimaging at 3-6 months, then annually for 1-2 years, with annual hormonal panels for 5 years 1, 5
• Canadian Urological Association (CUA): Reimaging at 12 months, then clinical follow-up for 4 years 1

The most recent and highest quality evidence (2023 CUA/AUA guidelines) supports no further follow-up for benign, non-functional adenomas <4 cm 1, 5, which represents the current standard of care.

Critical Pitfalls to Avoid

• Never skip initial hormonal evaluation even if imaging appears benign, as functional abnormalities occur in ~5% of radiologically benign incidentalomas 2, 3
• Do not perform adrenal mass biopsy routinely, as this is rarely indicated and carries risks including potential tumor seeding 1, 5
• Avoid unnecessary repeated imaging for small masses with confirmed benign characteristics (HU ≤10), as this increases radiation exposure, patient anxiety, and healthcare costs without clinical benefit 3
• Do not assume benignity in patients with history of extra-adrenal malignancy, as metastatic risk ranges from 25-72% depending on primary tumor type 3, 5

Special Population Considerations

If the patient has a history of extra-adrenal malignancy, the approach differs significantly with higher suspicion for metastatic disease requiring closer evaluation even for smaller lesions 3, 5.