Adrenal incidentaloma

The two key questions

1. Is it functional? Even a small adenoma can produce enough cortisol, aldosterone or catecholamines to matter.
2. Is it likely malignant? Size, density on CT and change over time drive this assessment.

Workup

• Hormone screen: overnight 1 mg dexamethasone suppression, plasma or urinary metanephrines, and aldosterone-to-renin ratio if high blood pressure or low potassium.³
• Imaging characterisation: dedicated adrenal CT (non-contrast density and washout) or MRI with chemical shift.
• Repeat imaging at 6 to 12 months if the lesion is indeterminate, to assess stability.

What usually happens

The European Society of Endocrinology clinical practice guideline provides a widely used framework:³

• Clearly benign, non-functioning lesion smaller than 4 cm: often no further imaging required; patient and GP are advised on red flags.
• Borderline or larger lesion: repeat imaging, additional hormone testing, or multidisciplinary discussion.
• Clear functional secretion, or imaging features suspicious for cancer: refer for surgery.

When surgery is considered

Surgery for an incidentaloma is considered when:

• Hormone testing shows autonomous cortisol, aldosterone or catecholamine production.
• Size is larger than about 4 cm, especially with worrying imaging features.³
• Growth is shown on serial imaging.

See robotic adrenalectomy for how the operation is done.