title: Uncommon thyroglossal duct cyst with inward tendency: a recommendation regarding ingrowth type.
abstract: OBJECTIVE
  There has been a growing number of case reports on uncommon thyroglossal duct cyst (TDC) extending into the oropharynx and/or laryngopharynx, which has often been misdiagnosed. We therefore examined the unfamiliar radiological and clinical characteristics of the cases in question so that we could advance the current store of knowledge.
  
  
  METHODS
  From January 2005 to May 2009, all cases with TDC seen at a tertiary hospital, whose clinical data and images included CT and MRI, were included in this retrospective study. Cases with an uncommon thyroglossal duct cyst were chosen and divided to three different sub-types: intra-laryngeal, intra-lingual, and trans-laryngeal, according to the clinical syndrome and the sites of masses.
  
  
  RESULTS
  In this study, 250 cases with TDC were collected, 21 (8.40%) of which presented extending images. Five such cases were of the intra-laryngeal type, with a mass lying close to the foramen cecum or posterior of the hyoid bone; 2 were classified as intra-lingual type, with a cyst in the tongue; 14 were classified as trans-laryngeal type, with a tumor occurring below the hyoid bone.
  
  
  CONCLUSIONS
  Uncommon TDCs tend to extend into the range of the respiratory tract. This novel type of ingrowth could facilitate early correct diagnosis and the formulation of an appropriate treatment plan.
authors.affiliation: Department of Otorhinolaryngology, Shanghai Eye, Ear, Nose & Throat Hospital, Fudan University (formerly Shanghai Medical University), 83 Fenyang Rd, Xuhui District, Shanghai 200031, PR China.
authors.forename: Li-Chun
authors.initials: LC
authors.lastname: Zhang
authors.forename: Hou-Yong
authors.initials: HY
authors.lastname: Kang
authors.forename: Tian-Yu
authors.initials: TY
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Sha
authors.forename: Fang-Lu
authors.initials: FL
authors.lastname: Chi
authors.forename: Le-Tian
authors.initials: LT
authors.lastname: Tan
authors.forename: Yao-Yao
authors.initials: YY
authors.lastname: Fu
authors.forename: Lei
authors.initials: L
authors.lastname: Jin
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003951:Diagnostic Errors / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007830:Larynx / Q000000981:diagnostic imaging* / Q000473:pathology; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D013955:Thyroglossal Cyst / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000628:therapy; D014057:Tomography, X-Ray Computed; D014059:Tongue / Q000000981:diagnostic imaging* / Q000473:pathology; D055815:Young Adult