Adrenal incidentalomas

  • Adrenal masses discovered during imaging for non-adrenal related causes
  • Commonest adrenal 'disorder'
  • Found during 1-5% of abdominal CT scans
  • 5-10% patients have non-functioning adrenal masses found at postmortem examination
  • Male to female ratio is equal
  • Most incidentalomas are benign and hormonally inactive
  • Few patients require adrenalectomy
  • Diagnostic assessment needs to evaluate:
    • Is the lesion hormonally active
    • Is the lesion malignant

Differential diagnosis in absence of prior malignancy

Diagnosis Percentage
Non-functioning cortical adenoma 55
Cortisol producing adenoma 8
Aldosteronoma 2
Adrenal carcinoma 5
Phaeochromocytoma 5
Metastases 20
Other (e.g. cyst, myelolipoma) 5

Adrenal metastases

  • Adrenal gland is a common site for metastases
  • Common primary sites are breast, lung, renal, melanoma, lymphoma
  • Often bilateral
  • If prior history of carcinoma then 10-40% of adrenal masses will be metastases
  • Risk of malignancy increases with size
  • Most malignant adrenal lesions are greater than 5 cm in diameter

Assessment of adrenal incidentalomas

  • Assessment of function requires:
    • Plasma dihydroepiandosterone
    • 24 hour urinary catecholamines and metanephrines
    • Low dose dexamethasone suppression test
    • Serum ACTH
    • If hypertension and hypokalaemia - standing serum aldosterone to renin ratio
  • Assessment of risk of malignancy requires:
    • CT or MRI scanning
    • On CT malignant lesions are irregular non-homogeneous and have high attenuation
    • On MRI malignant lesions have bright intensity on T2 weighed images
    • CT guided cytology may be useful
    • Need to exclude phaeochromocytoma prior to this procedure

Management of adrenal incidentalomas

  • If lesion is functioning patient requires adrenalectomy
  • Can be performed as either an open or laparoscopic procedure
  • Malignant lesions are best managed by open surgery
  • If non-functioning treatment depends on:
    • Size
    • Risk of malignancy
  • If more than 5 cm or imaging suggests malignancy consider surgery
  • If less than 5 cm or benign repeat CT at 3-6 months

Bibliography

Barzon L,  Boscaro M.  Diagnosis and management of adrenal incidentalomas.  J Urol 2000:  163:  395-407.

Brunt L M,  Moley J F.  Adrenal incidentaloma.  World J Surg 2001;  25:  905-913.

Graham D J,  McHenry C R.  The adrenal incidentaloma:  guidelines for evaluation and recommendations for management.  Surg Clin North Am 1998;  7:  749-764.

Murai M,  Baba S,  Nahashima J,  Tachibana M.  Management of incidentally discovered adrenal masses.  World J Urol 1999;  17:  9-14.

 

 
 

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