an adrenal incidentaloma is an adrenal mass , larger than 1  cm in diameter , detected on imaging studies performed for other indications than adrenal disease [ 1 , 2 ] . the increasing use of computed tomography ( ct ) scans and magnetic resonance imaging ( mri ) causes a marked increase in incidence of adrenal incidentalomas . in approximately 6% of all autopsies and 4% of all abdominal ct scans an incidentaloma of the adrenal gland is discovered [ 4 , 5 ] . the incidence of adrenal incidentaloma increases with age to an incidence of 10% in patients over 70 years old . adrenal incidentalomas are characterized by size , growth , imaging characteristics , and functional status . although rare , the normal function of the adrenal gland can be disrupted by adrenal incidentalomas . in most cases adrenal incidentalomas will be a small , nonhormonal active cortical adenoma , a benign impediment ( 80% ) . some adrenal incidentalomas cause hormonal hypersecretion ( 15% ) or appear to be a primary or secondary malignancy ( < 5% ) [ 6 , 7 ] . adrenal incidentalomas can cause disease by hypersecretion of hormones . conditions due to hormonal activity of adrenal incidentaloma include hypercortisolism , ( cushing 's syndrome ) , catecholamine excess ( pheochromocytoma ) , or hyperaldosteronism ( conn 's syndrome ) . subclinical autonomous cortisol hypersecretion is the most frequent hormonal abnormality in patients with adrenal incidentalomas . some of these patients eventually develop overt clinical cushing 's syndrome .   adrenal cortical adenomas with or without hormonal overproduction vascular lesions of the adrenal are suggestive of a medullary derived pheochromocytoma , but confirmation of a pheochromocytoma by serum or urine measurement of metanephrines is required to diagnose pheochromocytoma . not only will the radiologist appoint this finding in the radiology report , the radiologist will often also add a recommendation for the next diagnostic procedure . this retrospective study aims to get a clear view on the detection rate of adrenal incidentalomas on abdominal ct scans in our hospital , and the subsequent diagnostic procedures used after detection of this incidental finding . this retrospective study was designed to investigate the detection rate of adrenal incidentalomas on abdominal ct scans . for inclusion in this investigation , an adrenal incidentaloma was defined as an adrenal mass , greater than 1  cm in diameter , initially discovered by diagnostic imaging for a clinical condition not related to , or suspicious for , adrenal disease . two investigators learned from an expert radiologist to examine ct scans of the abdomen for primarily the adrenal gland . each investigator independently evaluated 180 ct scans out of 360 ct scans , of many patients , that were indicated for diagnostics of hepatic , pancreatic , or renal pathology between 2005 and 2007 . age , gender , indication for ct scan , and abnormalities in size or morphology , were noted .   at the time of examining the adrenal glands , the investigators were not aware of the content of ct scans ' radiology report or indication for ct scan . only after their own judgement about size and aspect of the adrenal glands , indication for ct scan and the radiology report an expert abdominal radiologist ( over 45,000 abdominal ct scans examined ) reviewed the ct scans marked by the investigators with abnormal adrenal glands in size or morphology and results were compared . if an adrenal incidentaloma was mentioned in the original radiology report , the patients ' record was reviewed to determine whether additional investigations , for example , hormonal studies , additional imaging , or interventional diagnostic studies , were performed after the ct . an interobserver test was performed to evaluate the resemblance of the way of evaluation between the investigators and expert radiologist . the ct scans performed for suspected hepatic , pancreatic , or renal pathology of 75 new patients , between 2007 and 2008 , were evaluated for this purpose . the interobserver variability was calculated with the friedman test , a non - parametric test for coupled observations , with independent observers . of the 360 patients studied , 206 ( 57% ) were men and 154 ( 43% ) were women . of the total of 360 patients , 4 patients were excluded because suspected adrenal pathology was also an indication for imaging in these patients . in the remaining 356 ct scans evaluated , the investigators discovered independently a total of 44 ( 12% ) abnormal adrenal glands in 42 patients ( 2 bilateral adrenal incidentalomas ) . each radiology report was checked for adrenal incidentalomas which were already noted . in 25 ( 7% ) of 356 patients an adrenal mass the expert radiologist reassessed the ct scans of 42 patients ; the radiologist discovered 17 patients with an adrenal incidentaloma . two patients had bilateral incidentalomas , giving a total of 19 adrenal incidentalomas not noted previously ( figure 1 ) . the total number of adrenal incidentalomas was 44/356 ( 12% ) in 42 patients . figure 3 shows an enlarged right adrenal not mentioned in the initial radiology report . in 64 of 356 ( 18% ) patients , a malignancy was the indication for imaging . patients with an adrenal incidentaloma were more likely to have a malignancy as indication for ct scan , 20/42 ( 48% ) . the 25 patients that had an adrenal incidentaloma mentioned in the initial radiology report were checked for additional diagnostic procedures performed . in 3/25 patients a follow - up ct scan none of these patients showed hormonal overproduction caused by the adrenal lesion . in 2 patients ( 8% ) a second ct scan was performed to exclude increase in adrenal size ; there was no growth of the adrenal lesion shown . one patient who underwent a hemihepatectomy had a simultaneous resection of the right adrenal incidentaloma . the interobserver variation was calculated using a friedman analysis test to exclude or to demonstrate a significant difference in perception between different readers . the friedman test showed that there was no statistically significant difference in perception between the investigators and the radiologist ( p = .867 ) . the detection of adrenal incidentalomas in this study was 7% and the actual incidence of adrenal abnormalities was 12% after focused assessment of ct scans . this is high compared to other studies and can be explained by the relatively large group of patients who underwent imaging examination because of a malignancy [ 7 , 11 ] . however , because of the absence of histological examination of the enlarged adrenal glands , it can not simply be concluded that these patients had metastases in the adrenal gland . the incidence of adrenal incidentalomas in the literature varies from 0.5% to 15% and depends mainly on the age of the investigated group [ 11 , 12 ] . only 6 of 25 ( 24% ) patients with an adrenal incidentaloma were further investigated with hormonal workup or imaging . one reason for the lack of additional diagnostic testing and treatment after detection of an adrenal incidentaloma is the lack of a clear evidence based guideline . also unfamiliarity with adrenal incidentalomas by the physician who has requested the ct scan will cause lack of additional screening . another reason for the lack of additional diagnostic testing of adrenal incidentalomas is the apparent lack of direct clinical consequences [ 13 , 14 ] . undetected hormonal hypersecretion will probably reveal itself in time and the chance of an adrenal carcinoma is low with 0.72/million / year [ 10 , 13 ] . because of this low risk of malignancy and because of the limited impact of hormonal overproduction in an asymptomatic patient , it is not clear whether a guideline for diagnosis and treatment of adrenal incidentaloma is necessary . such a guideline may cause an increase in diagnostic procedures with additional burden and uncertainty for the patient . a comprehensive cost - effectiveness study showed however that hormonal analysis of an adrenal incidentaloma is cost effective . the cost effectiveness of additional imaging of the adrenal gland is less clear in this study . in addition , the radiation dose to the patient becomes more important and therefore complementary imaging with an mri scan has its advantage . the optimal strategy for screening and followup of an adrenal incidentaloma is still under discussion . the guideline of the nih ( 2002 ) seems to be the best alternative in this debate , but the nih already recognized that the guideline is not based on hard evidence . ( table 1 ) protocols on the diagnostic procedures of adrenal incidentalomas are described in several other publications as well , without describing additional prospective data on the clinical results of these protocols [ 9 , 10 , 1518 ] . there are currently no prospective studies that have examined the effects of an additional diagnostic procedure for adrenal incidentalomas . following this study a guideline for additional screening and followup was made ( figure 2 ) . in each radiology report a recommendation will be added for every patient with an adrenal incidentaloma and the referring physician is pointed to a webpage with a brief summary about adrenal incidentalomas . this website also contains the brochure with information for patients , which can be printed .   in conclusion , it is not always noted by the radiologist and focused assessment of abdominal cts increased the detection rate of this abnormality form 7% to 12% . when detected and mentioned in the radiologist 's report , only a small percentage of patients receives additional hormonal or imaging investigations to determine the nature of the incidentaloma .
objectives . the aim of this study was to investigate the detection rate of adrenal incidentalomas and subsequent workup . design . 
 retrospective cohort study . methods . 
 two investigators evaluated the adrenals on abdominal ct scans . 
 abnormalities were compared to the original radiology reports and an experienced abdominal radiologist reviewed the ct scans . all additional imaging and laboratory tests were assessed . 
 results . 
 the investigators detected 44/356 adrenal incidentalomas ( 12% ) . in 25 patients 
 an adrenal incidentaloma had been noted in the radiology report . 
 the expert radiologist agreed on 19 incidentalomas in 17 patients , two with bilateral incidentalomas . 
 of the 25 incidentaloma patients , 4 ( 16% ) patients were screened for hormonal overproduction and 2 ( 8% ) patients had follow - up imaging studies . 
 conclusions . 
 12% of the patients had an adrenal incidentaloma ( 42 of 356 ) . 
 17 ( 40% ) had initially not been reported by the radiologist . 
 when diagnosed with an adrenal incidentaloma , only a small percentage of patients ( 16% ) is screened or undergoes repeated imaging ( 8% ) as proposed in the national institutes of health ( nih ) guidelines on adrenal incidentalomas .