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Adrenal Incidentalomas

Matthew Gonzalez


  • 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)
  • Supportive 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


  • All incidentalomas should be screened for pheochromocytoma (~3% incidence) before operative intervention (24h urine fractionated metanephrines, catecholamines, plasma fractionated metanephrines)
  • Cortisol secreting adenoma (~6% incidence) causing Cushing's syndrome: baseline serum DHEAS, low dose (1mg) overnight dexamethasone suppression test
  • Aldosterone secreting adenoma (<1% incidence) causing hyperaldosteronism: if hypertensive (HTN) or hypokalemic order plasma aldosterone and renin, confirmatory testing with sodium loading (oral vs IV) and 24h urine aldosterone, sodium, and creatinine


  • If benign appearing and not hormone producing: interval imaging in ~1 year, and repeat hormone work up
  • Unilateral adrenal incidentaloma
    • 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) + propranolol 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)
  • Cortisoloma: if clinical significant should undergo surgical removal, will need perioperative glucocorticoid administration to avoid iatrogenic adrenal insufficiency
  • Macroadenomas (masses >4cm) are usually malignant and 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.

Additional information

  • 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