title: Primary adenoid cystic carcinoma of the cervical trachea mimicking thyroid tumor: CT evaluation.
abstract: OBJECTIVE
  Our goal was to describe the CT characteristics of adenoid cystic carcinomas of the trachea mimicking thyroid tumors.
  
  
  METHODS
  Computed tomography of four patients with pathologically proved adenoid cystic carcinomas extending into the thyroid gland was retrospectively reviewed. One case was also examined with MR.
  
  
  RESULTS
  The masses encircling the trachea and circumferential thickening of the tracheal wall were demonstrated in all four cases. The longitudinal extent of the tracheal wall thickening was also demonstrated in all cases. The tumors had a broad base on the trachea and convex margin on the thyroid gland. They were all homogeneous, generally smoothly marginated, and isoattenuating on postcontrast CT scans.
  
  
  CONCLUSIONS
  Adenoid cystic carcinomas were usually seen on CT scans as homogeneous masses encircling the posterolateral trachea with thickening of the tracheal wall in the transverse and longitudinal planes. These CT characteristics may be helpful in the differential diagnosis of adenoid cystic carcinomas mimicking thyroid tumors.
authors.affiliation: Department of Diagnostic Radiology, Seoul National University College of Medicine, Seoul National University Hospital, Korea.
authors.forename: D G
authors.initials: DG
authors.lastname: Na
authors.forename: M H
authors.initials: MH
authors.lastname: Han
authors.forename: K H
authors.initials: KH
authors.lastname: Kim
authors.forename: K H
authors.initials: KH
authors.lastname: Chang
authors.forename: K M
authors.initials: KM
authors.lastname: Yeon
mesh_terms: D000328:Adult; D003528:Carcinoma, Adenoid Cystic / Q000000981:diagnostic imaging* / Q000473:pathology; D003413:Cricoid Cartilage / Q000473:pathology; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008297:Male; D009361:Neoplasm Invasiveness; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000473:pathology; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D014132:Trachea / Q000473:pathology; D014134:Tracheal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology