title: Malignancy risk analysis in patients with inadequate fine needle aspiration cytology (FNAC) of the thyroid.
abstract: BACKGROUND
  Thyroid fine needle aspiration cytology (FNAC) is the standard diagnostic modality for thyroid nodules. However, it has limitations among which is the incidence of non-diagnostic results (Thy1). Management of cases with repeatedly non-diagnostic FNAC ranges from simple observation to surgical intervention. We aim to evaluate the incidence of malignancy in non-diagnostic FNAC, and the success rate of repeated FNAC. We also aim to evaluate risk factors for malignancy in patients with non-diagnostic FNAC.
  
  
  METHODS
  Retrospective analyses of consecutive cases with thyroid non diagnostic FNAC results were included.
  
  
  RESULTS
  Out of total 1657 thyroid FNAC done during the study period, there were 264 (15.9%) non-diagnostic FNAC on the first attempt. On repeating those, the rate of a non-diagnostic result on second FNAC was 61.8% and on third FNAC was 47.2%. The overall malignancy rate in Thy1 FNAC was 4.5% (42% papillary, 42% follicular and 8% anaplastic), and the yield of malignancy decreased considerably with successive non-diagnostic FNAC. Ultrasound guidance by an experienced head neck radiologist produced the lowest non-diagnostic rate (38%) on repetition compared to US guidance by a generalist radiologist (65%) and by non US guidance (90%).
  
  
  CONCLUSIONS
  There is a low risk of malignancy in patients with a non-diagnostic FNAC result, commensurate to the risk of any nodule. The yield of malignancy decreased considerably with successive non-diagnostic FNAC.
authors.affiliation: Institute of Head & Neck and Education Studies, University Hospital Coventry and Warwickshire, Coventry, UK. taleb4u@yahoo.com
authors.forename: Talib
authors.initials: T
authors.lastname: Al Maqbali
authors.forename: Miroslav
authors.initials: M
authors.lastname: Tedla
authors.forename: Martin O
authors.initials: MO
authors.lastname: Weickert
authors.forename: Hisham
authors.initials: H
authors.lastname: Mehanna
mesh_terms: D044963:Biopsy, Fine-Needle; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D013961:Thyroid Gland / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D014463:Ultrasonography