Adrenal incidentalomas

Benign features include small size, an attenuation coefficient Hounsfield unit (HU) value <10, rapid washout of enhancement of lesions with HU>10, smooth outline, homogeneous with no calcification within the lesion.

All patients with an adrenal lesion require functional assessment as a non functioning small and benign appearing lesion may not require any further investigation or treatment. Adrenocortical adenomas can be clinically non functioning, or cause biochemical or subclinical Cushing’s or Conn’s syndrome. 

Renin:aldosterone ratios should be assessed at baseline. If the ratio is suggestive of Conn's, this will need to be confirmed by taking the patient off interfering medication and with selective venous sampling in many cases.

Spironolactone should then be considered as should surgical treatment.

2x24hr urinary free cortisol measurements, low dose dexamethasone suppression testing and serum ACTH levels should be taken in the first instance.

Further investigation and management of Cushing’s syndrome should then be discussed.

Small lesions with clearly benign characteristics, <3cm in size and with HU <10, should be discussed at a multidisciplinary meeting, and may be appropriately managed conservatively according to latest guidelines.

Annual biochemical assessment may be recommended but repeated imaging may not be necessary.

Repeat imaging should be considered and discussed by the multidisciplinary team for lesions >3cm.

Other lesions may have suspicious characteristics, for example those >5cm, with heterogeneous appearances, high Hounsfield unit values, low washout, calcification, or evidence suggestive of haemorrhage or infarction, and are best managed surgically as for possible malignancy.

Suspicious characteristics include size >5cm, heterogeneous appearances, high Hounsfield unit values, low washout, calcification, or evidence suggestive of haemorrhage or infarction. These lesions are invariably best treated surgically. Full biochemical assessment should still be performed prior to surgery in these cases as functioning lesions require specific pre operative preparation.

Adrenocortical carcinoma may frequently secrete androgens or glucocorticoids, and phaeochromocytomas may be hard to distinguish from malignant adrenal masses. Arrange urine metanephrines, urinary free cortisol, adrenal androgen profile, low dose dexamethasone testing, and random renin:aldosterone ratio in the first instance in all cases.

If it is uncertain whether an adrenal mass represents a metastasis of a known primary on imaging grounds, needle biopsy is helpful. This must never be performed until phaeochromocytoma has been ruled out biochemically.

Surgery should then be considered in all cases and discussed at a multidisciplinary meeting. Functionality should not alter the decision on whether surgery is appropriate, but will determine the pre operative preparation required.

These should all be managed and followed up in the usual way.

This should be managed according to the multidisciplinary team: generally with surgery and mitotane in the first instance and further surgery and chemotherapy as indicated.

Recent guidelines indicate that small, benign, non functioning adenomas may be managed conservatively with annual biochemical follow up and repeat imaging at six to 12 months, as appropriate and as determined by a multidisciplinary team discussion.