title: Hyalinizing trabecular tumor of thyroid: does frozen section prevent unnecessarily aggressive operation? Six new cases and a literature review.
abstract: BACKGROUND
  Fine-needle aspiration cytology (FNAC) is very accurate in detecting papillary thyroid carcinomas (PTCs). According to the Bethesda system for reporting thyroid cytopathology, the risk for malignancy is 97-99% when FNAC is used to diagnose PTC; the malignancy risk is 60-75% when FNAC results in suspected PTCs. The presence of hyalinizing trabecular tumor (HTT) of the thyroid can cause misdiagnosis because its cytological features mimic PTCs. However, the use of frozen section analysis can assist in the recognition of unique architecture features of HTT, and thus may help prevent the undertaking of an unnecessarily aggressive operation.
  
  
  METHODS
  We retrospectively reviewed all patients diagnosed with HTT by permanent histopathology from February 2009 to October 2013. After acquired agreement of the patients, we analyzed all data and reviewed another nine cases of HTT reported in the English-language medical literature to examine the efficacy of frozen section.
  
  
  RESULTS
  There were six patients included in our research (5 women and 1 man), with an average age of 48.8 years. Using frozen section, four patients were diagnosed with HTT and two patients were misinterpreted as PTC. Consequently, four patients had lobectomy and two patients had total thyroidectomy, with no surgical complications. Of the nine cases of HTT reviewed from the English literature, the use of frozen section showed three HTT cases, three PTC cases, two medullary thyroid carcinoma cases, and one deferral case. Overall, the use of frozen section as a diagnostic method prevented additional surgical resection in eight patients (53%).
  
  
  CONCLUSIONS
  Frozen section can sometimes but not always be used to diagnose HTT. When HTT is diagnosed by its trabecular pattern through the use of frozen section, it may prevent total thyroidectomy.
authors.affiliation: Division of General Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Shih-Ying
authors.initials: SY
authors.lastname: Sung
authors.affiliation: Department of Nuclear Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Tumor Board of Thyroid Cancer, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Hung-Yuan
authors.initials: HY
authors.lastname: Shen
authors.affiliation: Division of General Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Chung-Bao
authors.initials: CB
authors.lastname: Hsieh
authors.affiliation: Department of Surgery, University of California-San Francisco, San Francisco, CA, USA.
authors.forename: Quan-Yang
authors.initials: QY
authors.lastname: Duh
authors.affiliation: Department of Pathology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Ting-Fu
authors.initials: TF
authors.lastname: Su
authors.affiliation: Division of General Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: De-Chuan
authors.initials: DC
authors.lastname: Chan
authors.affiliation: Division of General Surgery, Department of Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC; Tumor Board of Thyroid Cancer, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC. Electronic address: judeshih@gmail.com.
authors.forename: Ming-Lang
authors.initials: ML
authors.lastname: Shih
mesh_terms: D000236:Adenoma / Q000473:pathology* / Q000601:surgery; D000328:Adult; D000368:Aged; D005260:Female; D005629:Frozen Sections; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013964:Thyroid Neoplasms / Q000473:pathology* / Q000601:surgery
keywords: frozen section; hyalinizing trabecular tumor; papillary thyroid cancer