title: The value of thyroid peroxidase immunohistochemistry for preoperative fine-needle aspiration diagnosis of the follicular variant of papillary thyroid cancer.
abstract: BACKGROUND
  With the use of May-Grunwald-Giemsa staining, cytologic features of the follicular variant of papillary thyroid cancers (FVPTCs) on thyroid fine-needle aspiration (FNA) often resemble those of hyperplastic and adenomatous nodules. Detection of reduced staining after thyroid peroxidase (TPO) immunohistochemistry with monoclonal antibody MoAb47 has been shown to be a helpful diagnostic marker. The purpose of this study was to assess the value of TPO immunohistochemistry for the diagnosis of FVPTC.
  
  
  METHODS
  Of 3505 patients with adequate FNA samples, 1576 patients underwent surgical procedures. Histologic examination of the surgical specimen demonstrated papillary thyroid cancer in 227 cases, including 42 FVPTCs (18%). The diagnostic accuracy of standard thyroid FNA and TPO immunohistochemistry, which we use routinely, was compared in these 42 FVPTCs.
  
  
  RESULTS
  Standard FNA allowed accurate diagnosis of malignancy in 32 of the 42 FVPTCs and in 170 of the 185 typical papillary thyroid cancers. TPO-immunohistochemistry staining was accurate in all 42 FVPTCs and in 182 of 185 typical PTCs.
  
  
  CONCLUSIONS
  FVPTC is a frequent source of false-negative results on standard thyroid FNA. This study shows that TPO immunostaining accurately demonstrates malignancy in these tumors.
authors.affiliation: Department of Pathology, INSERM U38, Marseille, France.
authors.forename: C
authors.initials: C
authors.lastname: De Micco
authors.forename: V
authors.initials: V
authors.lastname: Vassko
authors.forename: J F
authors.initials: JF
authors.lastname: Henry
mesh_terms: D000293:Adolescent; D000328:Adult; D001399:Azure Stains; D001707:Biopsy, Needle; D018265:Carcinoma, Papillary, Follicular / Q000201:enzymology* / Q000473:pathology* / Q000601:surgery; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007453:Iodide Peroxidase / Q000032:analysis*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care; D013964:Thyroid Neoplasms / Q000201:enzymology* / Q000473:pathology* / Q000601:surgery; D013965:Thyroidectomy
chemical_list: D001399:Azure Stains; D007453:Iodide Peroxidase