In a patient with a 2.8‑cm lipid‑rich adrenal nodule (5 Hounsfield units) and negative Cushing’s syndrome screening and no evidence of hormonal excess, is routine imaging surveillance required?

No Further Surveillance Required for This Benign Lipid-Rich Adenoma

For a patient with a 2.8-cm lipid-rich adrenal nodule (5 Hounsfield units), negative Cushing's screening, and no hormonal excess, no further imaging surveillance or functional testing is required. 1

Rationale for No Surveillance

Imaging Characteristics Confirm Benignity

• Lesions with ≤10 HU on unenhanced CT are definitively benign adenomas regardless of size, eliminating any concern for malignancy. 2
• The 5 HU attenuation in this case places the nodule well within the lipid-rich adenoma range, with studies showing 0% false-positive rate for malignancy at thresholds up to 10-16.5 HU. 1
• Homogeneous lesions with HU ≤10 do not require any additional imaging independent of size, per the most recent European Society of Endocrinology guidelines. 2

Size Does Not Override Benign Imaging Features

• While the 2.8-cm size falls below the traditional 4-cm threshold for concern, the lipid-rich imaging characteristics (5 HU) supersede size considerations for determining benignity. 1, 2
• In patients without known extra-adrenal malignancy, lesions <3 cm have only a 1.5% malignancy rate, and all malignant lesions in this population were >5 cm. 1
• The combination of lipid-rich imaging and size <4 cm definitively establishes this as a benign nonfunctioning adenoma. 1

Hormonal Testing Confirms Non-Functionality

• Negative Cushing's screening (presumably cortisol post-dexamethasone ≤50 nmol/L or ≤1.8 µg/dL) excludes mild autonomous cortisol secretion (MACS). 2
• The absence of symptoms or laboratory values consistent with hormonal excess rules out pheochromocytoma, aldosteronoma, or other functional tumors. 1
• Benign non-functional adenomas <4 cm with negative hormonal workup require no further follow-up imaging or functional testing. 1

Guideline-Based Recommendations

CUA/AUA 2023 Guidelines

The most recent Canadian Urological Association guidelines (endorsed by the American Urological Association) explicitly state:

• "Patients with benign non-functional adenomas <4 cm, myelolipomas and other small masses containing macroscopic fat detected on the initial work-up for an adrenal incidentaloma do not require further follow-up imaging or functional testing." 1

European Society of Endocrinology 2023 Guidelines

• Homogeneous lesions with HU ≤10 are benign and do not require additional imaging independent of size. 2
• These guidelines represent the most current international consensus on adrenal incidentaloma management. 2

Common Pitfalls to Avoid

Do Not Over-Surveil Benign Lesions

• Approximately 96% of adrenal incidentalomas are <4 cm, and 65% have attenuation values <10 HU, making them definitively benign. 3
• Unnecessary follow-up imaging exposes patients to radiation, cost, and anxiety without clinical benefit. 3
• Studies show that 95% of patients with adrenal incidentalomas do not require intervention, including medication changes or surgery. 3

Size Alone Should Not Trigger Surveillance

• Size is considered too unreliable to be used alone as a criterion for malignancy, particularly when imaging characteristics are definitively benign. 1
• The threshold of 4 cm for surveillance applies to indeterminate lesions, not lipid-rich adenomas. 1

Recognize When Hormonal Workup Is Complete

• Once Cushing's screening is negative and no clinical or laboratory evidence of hormonal excess exists, no further functional testing is needed. 1
• Repeat hormonal testing is only indicated if new symptoms develop or if the lesion grows significantly (>5 mm/year) on incidental imaging. 1

Clinical Context

What This Patient Has

• A lipid-rich adenoma (5 HU) measuring 2.8 cm
• Negative hormonal workup excluding MACS, pheochromocytoma, and aldosteronoma
• No symptoms of hormonal excess

What This Patient Does NOT Need

• No repeat CT or MRI imaging for surveillance 1, 2
• No repeat hormonal testing unless new symptoms develop 1
• No endocrinology referral for ongoing management 1
• No surgical consultation 1

Documentation and Patient Counseling

Inform the Patient

• This is a benign, non-functioning adrenal adenoma that requires no treatment or follow-up. 1, 2
• The patient should be reassured that the lipid-rich imaging characteristics definitively exclude malignancy. 2
• No lifestyle modifications or restrictions are necessary. 1

If Incidental Imaging Occurs in the Future

• If the lesion is incidentally visualized on future imaging for other reasons and grows <3 mm/year, no action is needed. 1
• If growth is >5 mm/year, repeat functional workup and consider adrenalectomy. 1
• Growth typically occurs within 12 months if it will occur at all, but this does not justify routine surveillance imaging. 3