title: Reclassifying formerly indeterminate thyroid FNAs using the Bethesda system reduces the number of inconclusive cases.
abstract: OBJECTIVE
  To evaluate the effectiveness of the Bethesda System for Reporting Thyroid Cytopathology (BSRTC) and to analyze the causes of unclear diagnoses following BSRTC adoption.
  
  
  METHODS
  According to the BSRTC, we reclassified cytologic samples originally diagnosed as 'indeterminate' with sequential surgical resection. Then, we analyzed the causes of cases, which were recategorized as 'atypia undetermined significance/follicular lesion of undetermined significance (AUS/FLUS)'.
  
  
  RESULTS
  According to the BSRTC, 154 'indeterminate' cases were reclassified as follows: unsatisfactory, n = 5 (3.2%); benign, n = 43 (27.9%); AUS/FLUS, n = 77 (50.0%); suspicious for a follicular neoplasm, n = 7 (7.1%); suspicious for a Hürthle cell neoplasm, n = 4 (2.6%); suspicious for malignancy, n = 15 (9.7%), and malignancy, n = 3 (1.9%). Then, the AUS/FLUS group was analyzed according to the scenarios proposed by the BSRTC. Fifty-nine (58.9%) cases of AUS/FLUS were due to suboptimal preparation. In addition, papillary microcarcinoma and coexisting Hashimoto's thyroiditis caused inconclusive diagnoses.
  
  
  CONCLUSIONS
  The BSRTC can be easily applied to thyroid fine-needle aspiration. We were able to reclassify indeterminate thyroid nodules into more detailed categories and thus reduce the number of cases classified as indeterminate. However, suboptimal preparation, papillary microcarcinoma, and coexisting Hashimoto's thyroiditis precluded cytopathologists from making definitive diagnoses.
authors.affiliation: Department of Pathology, Inha University Hospital, Incheon, South Korea.
authors.forename: Ju Young
authors.initials: JY
authors.lastname: Song
authors.forename: Young Chae
authors.initials: YC
authors.lastname: Chu
authors.forename: Lucia
authors.initials: L
authors.lastname: Kim
authors.forename: In Suh
authors.initials: IS
authors.lastname: Park
authors.forename: Jee Young
authors.initials: JY
authors.lastname: Han
authors.forename: Joon Mee
authors.initials: JM
authors.lastname: Kim
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000145:classification* / Q000175:diagnosis / Q000473:pathology*; D044963:Biopsy, Fine-Needle / Q000379:methods / Q000592:standards / Q000639:trends; D003937:Diagnosis, Differential; D050031:Hashimoto Disease / Q000145:classification / Q000175:diagnosis / Q000473:pathology; D006801:Humans; D010338:Pathology, Clinical / Q000379:methods* / Q000592:standards / Q000639:trends; D017410:Practice Guidelines as Topic / Q000592:standards; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013961:Thyroid Gland / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000145:classification* / Q000175:diagnosis / Q000473:pathology*