title: Follicular lesions of thyroid: a 5-year fine-needle aspiration experience.
abstract: BACKGROUND
  Fine-needle aspiration (FNA) of the thyroid is of limited value in discriminating between nonneoplastic and neoplastic lesions in approximately 5-29% of patients. Indeterminate lesions are due primarily to the overlapping cytologic features found in follicular lesions. In this report, the authors describe their experience with FNA biopsy of the thyroid, concentrating on the analysis of those aspirates placed in the follicular lesion category.
  
  
  METHODS
  A blinded, retrospective analysis of 92 patients who underwent FNA and were diagnosed with follicular lesions was performed by three of the authors (T.S.G., B.D.F., and M.O.) at a multihead microscope. A worksheet assessing a variety of cytologic and architectural features was filled out for each FNA patient. The reviewers then reached a consensus diagnosis.
  
  
  RESULTS
  The reviewers agreed with the reported FNA diagnosis of follicular lesion in 63 of the 92 patients studied. No distinguishing cytologic features predictive of the histologic outcome were found in any of these 63 patients. Seven patients were judged by the reviewers to have insufficient cells for evaluation. In the remaining 22 patients, the reviewers' diagnoses were in agreement with the histologic diagnoses in 17 patients. CONCLUSIONS. The authors found that there is a gray area in the cytologic diagnosis of patients with thyroid lesions by FNA due to inherent similarities at the light microscopic level. However, increased specificity may be achieved by careful attention to cytologic features and morphologic detail. Skillful application of FNA techniques, with the recovery of an adequate sample, will further decrease both interpretive errors and the number of patients diagnosed with "follicular lesions."
authors.affiliation: Department of Pathology, Los Angeles County and University of Southern California Healthcare Network, Los Angeles 90033, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: Greaves
authors.forename: M
authors.initials: M
authors.lastname: Olvera
authors.forename: B D
authors.initials: BD
authors.lastname: Florentine
authors.forename: A S
authors.initials: AS
authors.lastname: Raza
authors.forename: C J
authors.initials: CJ
authors.lastname: Cobb
authors.forename: D D
authors.initials: DD
authors.lastname: Tsao-Wei
authors.forename: S
authors.initials: S
authors.lastname: Groshen
authors.forename: P
authors.initials: P
authors.lastname: Singer
authors.forename: J
authors.initials: J
authors.lastname: Lopresti
authors.forename: S E
authors.initials: SE
authors.lastname: Martin
mesh_terms: D018263:Adenocarcinoma, Follicular / Q000473:pathology*; D001707:Biopsy, Needle / Q000379:methods; D005188:False Negative Reactions; D006801:Humans; D015588:Observer Variation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013959:Thyroid Diseases / Q000473:pathology*; D013964:Thyroid Neoplasms / Q000473:pathology*