Adrenal Incidentalomas and Subclinical Cushing's Syndrome: What Are the Criteria for Surgery?

Incidentalomas are adrenal masses unexpectedly found during abdominal imaging for other reasons. They do not constitute a final diagnosis, therefore, their genesis has to be established. The subclinical Cushing's syndrome is defined by a biochemically verifiable cortisol excess without specific clinical symptoms. However, there is so far no generally accepted biochemical definition of this syndrome. These patients suffer more frequently than the general population from metabolic syndrome with insulin resistance/impaired glucose tolerance/diabetes mellitus type 2, obesity, arterial hypertension, and hyperlipidemia. For incidentalomas, there is a definite indication for surgery when the mass leads to overt hormonal excess (pheochromocytoma, Conn's or Cushing's adenoma) or is suspected to be malignant. The subclinical Cushing's syndrome requires an individual indication for surgery because probably only a minority of patients will benefit from removal of the adenoma. If the adrenal mass is definitely benign, regular follow-up imaging is no longer regarded as mandatory. For endocrine inactive incidentalomas, endocrine work-up is recommended for the next 4 years. For the subclinical Cushing's syndrome the clinical evaluation is of utmost importance besides lab-test control.