title: Evaluation of Small Adrenal Incidental Nodules: Is Imaging Follow-Up Necessary?
abstract: Low incidence of adrenal cortical carcinoma in the general adult population has prompted a reevaluation of current protocol for the assessment of adrenal incidentalomas.
  
  
  
  To determine whether follow-up imaging for small (≤ 4 cm) incidental adrenal nodules is necessary for patients without known cancer.
  
  
  
  We performed a retrospective analysis of all patients found to have an incidental adrenal nodule on abdominal computed tomography (CT) scan during a 27-month period. The electronic medical record was reviewed to determine clinical outcomes in all patients with a minimum of 3 years of follow-up (mean follow-up = 6.7 years). Patients with a known primary cancer were excluded from the analysis unless they had a prior CT scan that documented an incidental adrenal nodule. Unenhanced CT attenuation was measured for all nodules, if available.
  
  
  
  A total of 392 patients with an incidental adrenal nodule had a mean (standard deviation [SD]) clinical follow-up of 6.7 (2.7) years. There were 200 men and 192 women with a mean (SD) age of 66.0 (13.2) years. None of these patients developed primary adrenocortical carcinoma during the follow-up period.Two hundred forty of these patients also had a minimum 3 years of imaging follow-up (mean [SD], 6.4 [2.4] years; range, 3.1-13.6 years). There were 173 left-sided and 91 right-sided nodules on index CT scan. There was no significant difference in the mean (SD) rate of growth between left- and right-sided nodules (0.1 [0.8] mm/year vs 0.1 [0.8] mm/year, p = 0.58). Mean unenhanced CT attenuation of adrenal nodules did not affect the likelihood of adrenal malignancy during follow-up.
  
  
  
  Patients with small incidental adrenal nodules do not require additional imaging to exclude the possibility of adrenocortical carcinoma.
authors.affiliation: Senior at Bryn Mawr College and was a Summer Research Associate in Diagnostic Imaging at the Moanalua Medical Center in HI. tokmyoung@sbcglobal.net.
authors.forename: Kara M
authors.initials: KM
authors.lastname: Young
authors.affiliation: Freshman at Yale College at Yale University and was a Summer Research Associate in Diagnostic Imaging at the Moanalua Medical Center in HI. mwong15@punahou.edu.
authors.forename: Michael K
authors.initials: MK
authors.lastname: Wong
authors.affiliation: Resident in Radiology at the University of California, Davis Medical Center in CA. mylesm@hawaii.edu.
authors.forename: Myles M
authors.initials: MM
authors.lastname: Mitsunaga
authors.affiliation: Associate Chief of Diagnostic Imaging at the Moanalua Medical Center in HI. hyo-chun.yoon@kp.org.
authors.forename: Hyo-Chun
authors.initials: HC
authors.lastname: Yoon
mesh_terms: D000293:Adolescent; D018268:Adrenocortical Carcinoma / Q000453:epidemiology / Q000503:physiopathology / Q000532:radiotherapy*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D033162:Incidental Findings; D008297:Male; D008485:Medical Audit; D008875:Middle Aged; D010818:Practice Patterns, Physicians'; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D055815:Young Adult