title: False-negative fine-needle aspiration of thyroid nodules cannot be attributed to sampling error alone.
abstract: BACKGROUND
  The goal of this study was to determine whether sampling error was the major cause for false-negative fine needle aspiration (FNA) results for thyroid nodules.
  
  
  METHODS
  Patients who underwent preoperative FNA between 1994 and 2008 were identified, and the results were compared with surgical pathology findings. Other related variables including nodule number and size were also recorded.
  
  
  RESULTS
  Excluding the microcarcinomas, the false-negative rate was 4% (19/479). Sampling errors occurred in only 4 (21%) cases in which the malignant nodule was not actually biopsied. Of the other 15 cases, 8 (53%) were solitary nodules, 8 (53%) were ≥4 cm in size, and 5 (33%) had underlying thyroiditis. Because of the missed diagnosis, 9 patients (47%) had lobectomy only as the initial surgery, which then required a completion thyroidectomy.
  
  
  CONCLUSIONS
  Sampling error is a minor cause for false-negative FNAs, suggesting that there are some inherent limitations to cytological evaluation of the thyroid.
authors.affiliation: Department of Surgery, Section of Endocrine Surgery, University of Wisconsin, Madison, WI 53792-7375, USA.
authors.forename: Xiao-Min
authors.initials: XM
authors.lastname: Yu
authors.forename: Priyesh N
authors.initials: PN
authors.lastname: Patel
authors.forename: Herbert
authors.initials: H
authors.lastname: Chen
authors.forename: Rebecca S
authors.initials: RS
authors.lastname: Sippel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle; D002648:Child; D003951:Diagnostic Errors / Q000706:statistics & numerical data*; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D016606:Thyroid Nodule / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy; D055815:Young Adult