Adrenal Incidentaloma

This past week's edition of NEJM includes a review article on Adrenal Incidentaloma... This makes a nice opportunity to talk about this frequently covered topic.

What is an adrenal incidentaloma?

An adrenal tumor discovered during imaging studies performed for other indications

What is the prevalence of adrenal incidentaloma?

6% in autopsy series
4% in patients receiving abdominal CT

What are the three questions you need to ask yourself when evaluating an incidentaloma?

1. Is it functional?
2. Is it a primary adrenal malignancy?
3. Is it a metastasis?

What are the first steps in the management of an adrenal incidentaloma?

1. History and Physical
2. Hormonal Evaluation

What hyperfunctional tumors or syndromes do you want to screen for in the initial evaluation?

1. Cushing's Syndrome, up to 20%
2. Pheochromocytoma, 5%
3. Aldosteronoma, 1%

What is Cushing's Syndrome?

Hypercortisolism

This may be subclinical, but manifested by hypertension, obesity, diabetes mellitus, and osteoporosis.

How can you evaluate for Cushing's Syndrome?

Overnight dexamethasone (1mg) suppression test

If this is positive (greater than 5ug/dL), the test may be confirmed with serum corticotropin, serum cortisol, 24-hr urine cortisol, and a high-dose dexamethasone suppression test.

When performing an adrenalectomy for a cortisol-secreting tumor, what considerations do you have to make?

The other adrenal will be suppressed, so perioperative glucocorticoids should be given.

How do you screen for pheochromocytoma?

Check a 24-hr urine sample for fractionated metanephrines and catecholamines.

What are confirmatory imaging studies for pheochromocytoma?

MIBG Scintigraphy
MRI showing high signal intensity when T2 weighted
CT showing heterogeneous and vascular tumor with increased attenuation

What is a MIBG Scan?

A nuclear study using I-131 MetaIodoBenzylGuanidine, a substrate that is concentrated in catecholamine storage vesicles. Thus study may be helpful for evaluating patients for pheochromocytomas and neuroblastomas.

How do you screen for aldosteronoma?

The patient is typically hypertensive with hypokalemia
Assess plasma aldosterone:renin ratio (morning levels, off spironolactone, eplerenone, or amiloride)

What is a saline infusion test?

This is a confirmatory test for primary aldosteronism, where saline loading (2L bolus) fails to suppress plasma aldosterone levels below 8.5 mg/dL after having the patient lie supine for 4hrs.

Once you are assured that the incidentaloma is not hormonally active, what are you still suspicious of?

1. Adrenocortical carcinoma
2. Metastasis

What are suspicious findings on CT?

Heterogeneous, vascular lesion with irregular margins, necrosis, hemorrhage, or calcifications, high signal attenuation with slow washout of contrast material

Adrenal adenomas have high lipid content, leading to low attenuation. They also have rapid washout of contrast material (more than 50% in 10 minutes)

What are suspicious findings on MRI?

Hyperintensity relative to the liver on a T2-weighted image

Why does size matter?

Lesions greater than 4cm have a 90% sensitivity and 24% specificity for adrenocortical carcinoma. Adrenalectomy is recommended for these lesions.

What tumors metastasize to the adrenals?

Lung, kidney, colon, breast, esophagus, pancreas, liver, and stomach.
Often bilateral

What are considerations to be made before choosing to FNA an adrenal tumor?

Pheochromocytoma must first be ruled out to avoid a hypertensive crisis. In general, should be reserved for patients who are not candidates for surgical resection, but where the results of biopsy may impact therapy.

What are the most likely diagnoses with bilateral incidentalomas?

1. Metastatic disease
2. Congenital adrenal hyperplasia
3. Bilateral cortical adenomas

What are recommendations for the follow-up of a patient with a nonfunctioning incidentaloma?

Repeat imaging studies at 6, 12, and 24 months
Repeat hormonal evaluation yearly for 4 years
Adrenalectomy for lesions greater than 4cm, or if enlarges more than 1cm during observation, or if patient develops evidence of autonomous hormonal secretion

Late... SG

Sources:
Norton's Surgery: Basic Science and Clinical Evidence
Mastery of Surgery, 5th ed.
Young WF. The Incidentally Discovered Adrenal Mass. NEJM 2007; 356(6): 601-610.