title: Scintigraphic detection of dual ectopic thyroid tissue: experience of a Chinese tertiary hospital.
abstract: OBJECTIVE
  To assess scintigraphic pattern, clinical indication and relevance of dual ectopic thyroid tissue (ETT). Literature is reviewed for such cases.
  
  
  METHODS
  In this 5-year retrospective study, we reviewed all thyroid scintigraphies in our data base. Patients diagnosed with suspected ETT were identified. Literature is reviewed. Statistics were done by one-way analysis of variance and least significant difference test.
  
  
  RESULTS
  From 11905 thyroid scintigraphies during the 5-year period, we retrieved 121 patients eligible for analysis. The top two indications were assessing a palpable front neck mass to determine whether it was an ETT, and primary hypothyroidism. Patients were divided into 3 groups. Group 1 with single ETT (83 cases); group 2 with dual ETT (6 cases) and group 3 with athyroid (32 cases). Age and thyroid hormones were highest in group 2, and lowest in group 3. Thyrotropin was highest in group 3, and lowest in group 2. Thyroxine was given to hypothyroid patients, while no surgery was performed. There were 42 published cases with dual ETT, most of whom were under 30 years old. 38.10% of them were euthyroid, 33.33% hypothyroid, and 21.43% subclinical hypothyroid. Most frequent ectopic positions included lingual (33.73%), sublingual (27.71%) and subhyoid (22.89%).
  
  
  CONCLUSIONS
  In our cohort, incidence of dual ETT was 0.05% if the denominator was total number of thyroid scintigraphies. The incidence was 4.96% if the denominator was the number of patients with suspected ETT. Important clinical indication is a front neck palpable mass suggestive of an ETT. Important clinical relevance of recognizing the dual ETT pattern is to avoid inappropriate surgery. After reviewing all published cases, we find dual ETT is often seen in young patients. Most of such patients are euthyroid or mildly hypothyroid. Thyroid ectopia often resides in lingual, sublingual and subhyoid areas.
authors.affiliation: Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Zhaowei
authors.initials: Z
authors.lastname: Meng
authors.affiliation: Department of Mathematics, Statistics and Printing Press, Tianjin Normal University, Tianjin, Tianjin, P. R. China.
authors.forename: Shanshan
authors.initials: S
authors.lastname: Lou
authors.affiliation: Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Jian
authors.initials: J
authors.lastname: Tan
authors.affiliation: Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Jia
authors.affiliation: Department of Pediatrics, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Rongxiu
authors.initials: R
authors.lastname: Zheng
authors.affiliation: Department of Pediatrics, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Geli
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Endocrinology, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Mei
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Department of Endocrinology, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Qing
authors.initials: Q
authors.lastname: He
authors.affiliation: Department of Radiology, Tianjin Medical University General Hospital, Tianjin, Tianjin, P. R. China.
authors.forename: Dong
authors.initials: D
authors.lastname: Li
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002681:China; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011877:Radionuclide Imaging; D012189:Retrospective Studies; D062606:Tertiary Care Centers; D050033:Thyroid Dysgenesis / Q000000981:diagnostic imaging*; D055815:Young Adult
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