The prevalence of adrenal incidentaloma in routine clinical practice

The prevalence of adrenal incidentaloma (AI) on computed tomography (CT) in the general population has been reported to be as high as 4.2%. However, many of the previous studies in this field utilised a prospective approach with analysis of CT scans performed by one or more radiologists with a specialist interest in adrenal tumours and a specific focus on identifying the presence of an adrenal mass. A typical radiology department, with a focus on the patient's presenting complaint as opposed to the adrenal gland, may not be expected to diagnose as many adrenal incidentalomas as would be identified in a dedicated research protocol. We hypothesised that the number of AI reported in routine clinical practice is significantly lower than the published figures would suggest. We retrospectively reviewed the reports of all CT thorax and abdomen scans performed in our hospital over a 2 year period. 3,099 patients underwent imaging, with 3,705 scans performed. The median age was 63 years (range 18-98). Thirty-seven true AI were diagnosed during the time period studied. Twenty-two were diagnosed by CT abdomen (22/2,227) and 12 by CT thorax (12/1,478), a prevalence of 0.98 and 0.81% with CT abdomen and thorax, respectively, for AI in routine clinical practice.