Prospective evaluation of tumor size and hormonal status in adrenal incidentalomas

Because of the increased use of imaging interventions, more subjects have been diagnosed with adrenal incidentaloma in recent years.

To evaluate the risk of mass enlargement, hormone hypersecretion and development of adrenal carcinomas during short-term followup.

There were 317 subjects with incidentally discovered adrenal tumors in the registry. Forty subjects were excluded because of clinically overt hormone secretion at diagnosis and subjects with complete data were included in radiological (no.=150) and hormonal (no.=150) follow- up. Radiological evaluation was performed with computed tomography (CT) and/or magnetic resonance imaging (MRI). There were 143 subjects with adrenal adenomas and 7 subjects with other tumor types (cyst or myelolipoma). Median follow-up duration was 24 months.

Increase in tumor size was detected in 25 subjects (17.4%) with adenomas and 1 subject with adrenal myelolipoma (14.3%). Decrease in tumor size was found in 7 subjects (4.8%) with adrenal adenomas. One patient was diagnosed with adrenocortical carcinoma during follow-up. In subjects with non-functioning adrenal adenoma (NFA, no.=120) or subclinical Cushing syndrome (sCS) (no.=30), no subject developed clinically overt hormone hypersecretion, while 8 (6%) subjects in the NFA group developed sCS. Tumor diameter and follow-up duration were significantly higher in subjects who developed sCS.

In conclusion, we demonstrated that, despite being infrequent, adrenal tumors may increase in size, develop overt or subclinical hormone secretion or feature malignant transformation. Therefore, radiological and hormonal follow-up should be recommended to the patients. More investigations are needed for the establishment of long-term follow-up protocols.