title: Thyroid nodules with nondiagnostic results on repeat fine-needle aspiration biopsy: which nodules should be considered for repeat biopsy or surgery rather than follow-up?
abstract: OBJECTIVE
  The goal of this study was to assess the clinicopathologic and ultrasonographic features of thyroid nodules with nondiagnostic results on repeat ultrasonography (US)-guided fineneedle aspiration biopsy (FNAB) according to size and the number of suspicious findings and to determine the proper management of nodules with consecutive nondiagnostic results.
  
  
  METHODS
  This retrospective study included 297 nodules with nondiagnostic results on repeat FNAB that were evaluated by US over the course of at least 12 months of follow-up, a follow-up biopsy, or an operation. We compared clinical and US variables between benign and malignant nodules in thyroid nodules with repeat nondiagnostic results.
  
  
  RESULTS
  The comparison of benign and malignant nodules with repeat nondiagnostic results revealed that age, marked hypoechogenicity, irregular or microlobulated margins, microcalcifications, and nonparallel shape were significantly associated with malignancy. Multivariate logistic regression analysis in malignant nodules revealed that microcalcifications and irregular or microlobulated margins were independently associated with malignancy. Among them, only irregular or microlobulated margins were independently significant as a predictor of malignancy in repeatedly nondiagnostic nodules measuring >10 mm. Using receiver operating characteristic analysis, the best cutoff value for the "number of suspicious findings" between benign and malignant nodules was three in nodules of all sizes, three in nodules measuring ≤10 mm, and two in nodules measuring >10 mm.
  
  
  CONCLUSIONS
  Irregular or microlobulated margins may be the most frequent US features in repeatedly nondiagnostic nodules >10 mm. The presence of "two or more suspicious findings" can be used as the cutoff for distinguishing benign and malignant nodules.
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Na Lae
authors.identifier: 0000-0002-7299-3051
authors.initials: NL
authors.lastname: Eun
authors.affiliation: Department of Radiology, Dongjak Kyunghee Hospital, Seoul, Korea.
authors.forename: Mi Ri
authors.identifier: 0000-0002-7015-7826
authors.initials: MR
authors.lastname: Yoo
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hye Mi
authors.identifier: 0000-0002-3054-1532
authors.initials: HM
authors.lastname: Gweon
authors.affiliation: Department of Radiology, Korea University Ansan Hospital, Korea University College of Medicine, Ansan, Korea.
authors.forename: Ah Young
authors.identifier: 0000-0002-4747-9480
authors.initials: AY
authors.lastname: Park
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Jeong-Ah
authors.identifier: 0000-0003-4949-4913
authors.initials: JA
authors.lastname: Kim
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Ji Hyun
authors.identifier: 0000-0002-7787-780X
authors.initials: JH
authors.lastname: Youk
authors.affiliation: Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hee Jung
authors.identifier: 0000-0002-3054-1532
authors.initials: HJ
authors.lastname: Moon
authors.affiliation: Department of Surgery, Thyroid Cancer Center, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hang-Seok
authors.identifier: 0000-0002-5162-103X
authors.initials: HS
authors.lastname: Chang
authors.affiliation: Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Eun Ju
authors.identifier: 0000-0002-7895-0335
authors.initials: EJ
authors.lastname: Son
keywords: Biopsy, fine-needle; Thyroid nodule; Ultrasonography