title: Inter- and intraobserver reproducibility of thyroid fine needle aspiration cytology: an analysis of discrepant cases.
abstract: OBJECTIVE
  To determine the inter- and intraobserver reproducibility and analyse the discrepant cases of fine needle aspiration cytology (FNAC) of the thyroid.
  
  
  METHODS
  Cases of thyroid FNAC with a corresponding histological diagnosis were reviewed regarding the original cytological diagnoses by two observers. The final cytological diagnoses (FCD) included both concordant and consensus diagnoses. The inter- and intraobserver reproducibility and efficacy of thyroid FNAC were calculated based on the FCD.
  
  
  RESULTS
  A total of 97 FNAC cases with corresponding histopathological specimens were analysed. Although inter- and intraobserver disagreement in the cytological diagnoses occurred in about one-quarter of the cases analysed (24.7% and 23.7%, respectively), a substantial level of diagnostic interobserver (kappa = 0.71) and intraobserver (kappa = 0.66) reproducibility was observed. The efficacy of the method was 94.4%. Disagreement in the diagnosis was detected in 24 cases (24.7%), most of them (41.7%) for follicular lesions. Discordant cytological diagnoses between the two observers were represented by six (16.2%) of the 37 cases with an FCD of colloid nodule, five (41.7%) of the 12 cases of cellular follicular lesion, all three cases of follicular neoplasm, in two (6.3%) of the 32 cases of PTC, one (16.7%) of six cases of follicular neoplasm with a predominance of Hürthle cells and in one case of poorly differentiated neoplasia. Similarly, major disagreement in intraobserver cytological diagnoses was observed for the diagnosis of follicular lesions: 18 (78.3%) of a total of 23 discordant cases.
  
  
  CONCLUSIONS
  As discrepancies in the cytopathological diagnosis can have repercussions in the management of patients, all cases with a cytological diagnosis of follicular lesions/neoplams should be reviewed in multidisciplinary meetings thus minimizing interobserver variability.
authors.affiliation: Department of Pathology, Hospital das Clínicas, University of São Paulo, São Paulo, Brazil. regerhard@terra.com.br
authors.forename: R
authors.initials: R
authors.lastname: Gerhard
authors.forename: G
authors.initials: G
authors.lastname: da Cunha Santos
mesh_terms: D044963:Biopsy, Fine-Needle; D003951:Diagnostic Errors; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results; D013959:Thyroid Diseases / Q000473:pathology*; D013961:Thyroid Gland / Q000473:pathology*