title: Incidental thyroid abnormalities identified on neck US for non-thyroid disorders.
abstract: BACKGROUND
  Incidental thyroid abnormalities detected on US examinations in children have not been well documented.
  
  
  OBJECTIVE
  To determine prevalence of incidental thyroid abnormalities depicted by US in children and to describe the spectrum of appearances.
  
  
  METHODS
  Retrospective analysis of clinical and US findings in children who had neck US from January 2006 to December 2007.
  
  
  RESULTS
  Of 1,228 neck US exams, thyroid was depicted in 287 children (mean age = 6.2 years). Incidental thyroid abnormalities were detected in 52 (18%) (mean age = 8.1 years). In 35 there were small (<4 mm), well-defined cysts, some with a hyperechoic punctate focus. In nine there were hypoechoic, solid nodules with smooth, straighter margins with echogenicity similar to thymus, suggesting intrathyroid ectopic thymus (mean age = 2.5 years). In three others there were tiny hyperechoic foci without nodules. Other abnormalities included hypoechoic target-like lesions (n = 2), isoechoic nodule (n = 1), multiple hypoechoic foci (n = 1) and non-visualized thyroid lobe resulting from adjacent abscess (n = 1). None of the children developed thyroid dysfunction or malignancy.
  
  
  CONCLUSIONS
  There is a spectrum of incidental thyroid abnormalities in children. These US findings should be interpreted cautiously, avoiding unnecessary referrals and investigations. Intrathyroid ectopic thymus is more common than previously thought, occurs much more frequently in younger boys and should be considered if the lesion has US characteristics of thymus.
authors.affiliation: Department of Diagnostic Imaging, The Hospital for Sick Children and University of Toronto, 555 University Ave., Toronto, ON M5G 1X8, Canada.
authors.forename: Shivaram
authors.initials: S
authors.lastname: Avula
authors.forename: Alan
authors.initials: A
authors.lastname: Daneman
authors.forename: Oscar M
authors.initials: OM
authors.lastname: Navarro
authors.forename: Rahim
authors.initials: R
authors.lastname: Moineddin
authors.forename: Stacey
authors.initials: S
authors.lastname: Urbach
authors.forename: Denis
authors.initials: D
authors.lastname: Daneman
mesh_terms: D002648:Child; D005260:Female; D006801:Humans; D033162:Incidental Findings; D008297:Male; D009333:Neck / Q000000981:diagnostic imaging*; D009864:Ontario / Q000453:epidemiology; D015995:Prevalence; D018570:Risk Assessment; D012307:Risk Factors; D017678:Sex Distribution; D013959:Thyroid Diseases / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D014463:Ultrasonography / Q000706:statistics & numerical data*