title: Malignancy risk stratification in thyroid nodules with benign results on cytology: combination of thyroid imaging reporting and data system and Bethesda system.
abstract: BACKGROUND
  The indications of repeat fine-needle aspiration (FNA) for thyroid nodules with benign results of the Bethesda system were investigated.
  
  
  METHODS
  A total of 1,398 nodules were classified according to the Thyroid Imaging Reporting and Data System (TIRADS). TIRADS category 3 included nodules without solidity, hypoechogenicity or marked hypoechogenicity, microlobulated or irregular margins, microcalcifications, and taller-than-wide shape on ultrasonography (US). Categories 4a, 4b, 4c, and 5 included nodules with one, two, three or four, or five suspicious US features, respectively. The malignancy risks, and odds ratio (OR) with 95 % confidence interval (CI) were calculated. Analyses were performed for all nodules, nodules >10 mm, and nodules ≤10 mm.
  
  
  RESULTS
  Of 1.398 nodules, 43 (3.1 %) were malignanct. The malignancy risks of benign nodules with categories 3, 4a, and 4b were 0.7, 1.2, and 0.7 %, respectively, whereas those for nodules with categories 4c and 5 were 9.8 and 22.2 %, respectively. The ORs of nodules with categories 4c and 5 were 19.4 (95 % CI 5.0-76.2) and 50.6 (95 % CI 10.4-245.0), respectively. In nodules >10 mm, the malignancy risks of categories 4c and 5 were 2.7 and 20 %, respectively, and the ORs were 10.7 (95 % CI 1.2-93.7) and 236.1 (95 % CI 12.6-4426.4), respectively. In nodules ≤ 10 mm, the malignancy risks of categories 4c and 5 were 12.6 and 22.6 %, respectively, and the ORs were 10.1 (95 % CI 1.3-78.0) and 18.9 (95 % CI 2.1-168.9), respectively.
  
  
  CONCLUSIONS
  Repeat US-guided FNA should be considered in benign thyroid nodules with three or more suspicious US features regardless of size.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Moon
authors.forename: Eun-Kyung
authors.initials: EK
authors.lastname: Kim
authors.forename: Jin Young
authors.initials: JY
authors.lastname: Kwak
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology*; D000328:Adult; D044963:Biopsy, Fine-Needle; D018276:Carcinoma, Medullary / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology*; D002291:Carcinoma, Papillary / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology*; D006801:Humans; D061705:Image-Guided Biopsy; D008875:Middle Aged; D018570:Risk Assessment; D013964:Thyroid Neoplasms / Q000145:classification / Q000000981:diagnostic imaging / Q000473:pathology*; D016606:Thyroid Nodule / Q000145:classification / Q000000981:diagnostic imaging* / Q000473:pathology*; D047368:Tumor Burden; D014463:Ultrasonography