Adrenal Incidentaloma

During the evaluation of adrenal incidentaloma, two questions need to be asked:
1) is the the lesion hormonally active?
2) does it have radiologic characteristics suggestive of a malignant lesion?

Is the lesion hormonally active?

• The patient should be tested for hypercortisolism, hyperaldosteronism ( if hypertensive ) and phaeochromocytoma.

• Hypercortisolism - the simplest screening test is a 1 mg overnight dexamethasone suppression test. If clinical suspicion is high, such as in patients with hypertension, obesity, diabetes mellitus or osteoporosis, 3 tests ( salivary cortisol, dexamethasone suppression test and 24 hr urinary free cortisol ) can be used.

• Phaeochromocytoma - should undergo measurement of plasma fractionated metanephrines and normetanephrines or 24 hr total urinary metanephrines and fractionated catecholamines.

• Aldosteronism - an aldosterone-to-renin ratio should be performed and if > 20, further confimation by demonstrating lack of aldosterone suppression with salt loading.

Does it have radiologic characteristics suggestive of a malignant lesion?

• Although size should not be used as the only parameter to guide treatment, a 4-cm cutoff had a 93 percent sensitivity of detecting adrenocortical carcinoma, even though specificity was limited (76 percent of masses larger than 4 cm in diameter were benign). As a result, surgical removal of masses larger than 4 cm, particularly in younger patients is recommended.

• A homogeneous adrenal mass <4>50 percent at 10 minutes) is very likely to be a benign cortical adenoma.

• The imaging characteristics that suggest adrenal carcinoma or metastases include: irregular shape, inhomogeneous density, high unenhanced CT attenuation values (>20 HU), delayed contrast medium washout (eg, <50>4 cm, and tumor calcification.