title: Value of immunohistochemistry in the detection of BRAF(V600E) mutations in fine-needle aspiration biopsies of papillary thyroid carcinoma.
abstract: BACKGROUND
  Fine-needle aspiration biopsy (FNAB) is important in the diagnostic establishment of suspicious thyroid nodules. In thyroid neoplasms, mutation of the BRAF gene occurs rather exclusively in papillary thyroid carcinoma (PTC) and results in>98% of the cases in V600E amino acid substitution. In the current study, the authors investigated the diagnostic value of a recently described monoclonal antibody that detects this specific mutation on FNAB specimens from patients with PTC.
  
  
  METHODS
  BRAF(V600E) status of FNAB cell blocks from 55 patients with PTC was analyzed by immunohistochemistry (IHC) with the new BRAF(V600E) antibody (clone VE1) and by Sanger sequencing (SaS). In discrepant cases, ultra-deep sequencing was also performed. Available corresponding histological specimens were investigated by IHC and, in selected cases, with SaS as well.
  
  
  RESULTS
  All cases yielded evaluable IHC staining results of the cell block sections with good interobserver agreement (kappa value, 0.650). Ten tumors (18.2%) demonstrated no staining, 10 tumors (18.2%) demonstrated equivocal staining, 25 tumors (45.4%) demonstrated moderate staining, and 10 tumors (18.2%) demonstrated strong staining. SaS was able to be performed in 48 cases. Nineteen cases demonstrated wild-type BRAF and 29 cases were found to have the BRAF(V600E) mutation. After performing ultra-deep sequencing 1 false-positive and 2 false-negative VE1 IHC cases remained, resulting in a sensitivity of 93.8% and a specificity of 93.8%.
  
  
  CONCLUSIONS
  BRAF(V600E) mutations in FNAB specimens from patients with PTC can be reliably detected in most cases by IHC with a new mutation-specific antibody. Interpretation of VE1 IHC staining results on cell block slides of PTC can be difficult in some cases.
authors.affiliation: Institute of Surgical Pathology, University Hospital, Zurich, Switzerland.
authors.forename: Anne-Katrin
authors.initials: AK
authors.lastname: Zimmermann
authors.forename: Ulrike
authors.initials: U
authors.lastname: Camenisch
authors.forename: Markus P
authors.initials: MP
authors.lastname: Rechsteiner
authors.forename: Beata
authors.initials: B
authors.lastname: Bode-Lesniewska
authors.forename: Matthias
authors.initials: M
authors.lastname: Rössle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044963:Biopsy, Fine-Needle / Q000379:methods; D002277:Carcinoma / Q000235:genetics* / Q000473:pathology* / Q000601:surgery; D002291:Carcinoma, Papillary; D016009:Chi-Square Distribution; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*; D015203:Reproducibility of Results; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D000077273:Thyroid Cancer, Papillary; D013964:Thyroid Neoplasms / Q000235:genetics* / Q000473:pathology* / Q000601:surgery
chemical_list: C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf
keywords: BRAF mutation; Sanger sequencing; fine-needle aspiration biopsy; immunohistochemistry; papillary thyroid carcinoma; ultra-deep sequencing