Adrenal Incidentalomas

Endocrinology Editor: Aamuktha Karla, MD
Reviewed by: Angel Morvant, MD
Section Editor: Matthew Gonzalez

Background

  • Adrenal mass >1cm, discovered by chance on radiographic imaging
  • Less than 1% are malignant
  • Supportive of benign: <4cm in size, smooth borders, homogenous appearance, <10 HU (Hounsfield units), rapid (>50% washout) contrast washout (on "adrenal phase" imaging)
  • Suggestive of malignancy: >4cm in size, irregular borders, > 20 HU on unenhanced CT, delayed contrast washout (<50% washout), tumor calcifications, increase in size over time, presence in young pts and hx cancer

Evaluation

  • All incidentalomas should be screened for pheochromocytoma (~3% incidence) before operative intervention if imaging features are suggestive of pheochromocytoma or malignancy (24h urine fractionated metanephrines, catecholamines, plasma fractionated metanephrines).
  • Cortisol secreting adenoma causing Cushing's syndrome or mild autonomous cortisol secretion: baseline serum DHEAS, low dose (1mg) overnight dexamethasone suppression test (DST).
  • Do not perform DST if there is suspicion of pheochromocytoma due to risk of precipitating catecholaminergic crisis.
  • Aldosterone secreting adenoma (<1% incidence) causing hyperaldosteronism: if hypertensive (HTN) or hypokalemic, order plasma aldosterone and renin, confirmatory testing with sodium loading followed by 24h urine aldosterone, sodium, and creatinine OR saline infusion test.

Management

  • Unilateral adrenal incidentaloma:
    • If benign appearing and not hormone-producing: interval imaging in ~1 year, and repeat hormone work up.
    • If progression free (stable size, and not hormone producing) can consider monitoring cessation after 4 years.
    • Pheochromocytomas should undergo surgical evaluation for removal.
    • Alpha blockade (phenoxybenzamine or other alpha blocker) + beta blockade prior to resection to avoid HTN crisis.
    • Aldosteronoma: should undergo surgical evaluation for definitive treatment; if unable to undergo surgery can use mineralocorticoid antagonist (e.g. spironolactone).
    • Cortisol-producing adenoma: if clinically significant should undergo surgical removal.
    • Macroadenomas (masses >4cm) should be considered for surgical resection due to higher risk of carcinoma.
  • Bilateral adrenal incidentalomas:
    • Surgical evaluation + will need adrenal venous sampling to confirm laterality in hormone producing tumors.
    • There can be coexisting adrenal incidentaloma and bilateral secretion of aldosterone – may require adrenal venous sampling to confirm.
    • Not all hyperaldosterone states will have both HTN and hypokalemia.
    • Subclinical Cushing's syndrome may be present based on initial dexamethasone suppression test, perform additional testing to determine if clinically significant.
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