Adrenal adenoma

How it presents

Three patterns are common:

• Non-functioning adenoma. No symptoms. Discovered on CT or MRI done for another reason (see incidentaloma).
• Cortisol-producing adenoma. Autonomous cortisol secretion, ranging from subclinical to overt Cushing's syndrome.
• Aldosterone-producing adenoma. Conn's syndrome - difficult-to-control high blood pressure, often with low potassium.

How it is investigated

Every adrenal adenoma needs two things before a decision is made about surgery: hormone testing and imaging characterisation.

• Hormone screen. Overnight 1 mg dexamethasone suppression, aldosterone-to-renin ratio, and plasma metanephrines to rule out phaeochromocytoma before any biopsy or operation.³
• Imaging. Dedicated adrenal CT looking at non-contrast density (Hounsfield units) and washout, or MRI with chemical shift. Adenomas are usually lipid-rich, small and have low density on unenhanced CT.

When surgery is considered

Surgery is generally offered when:

• The adenoma is hormone-active (cortisol, aldosterone or androgens).
• It is larger than about 4 cm, or shows worrying imaging features.³
• It grows on repeat imaging.

For small, silent, clearly benign adenomas, active surveillance is reasonable, guided by European Society of Endocrinology advice.³

How the operation is done

Most adrenal adenomas are now removed with minimally invasive surgery. The robotic approach is preferred in many centres because of enhanced precision and vessel control.⁴ See robotic adrenalectomy for the full procedure detail.