title: HER 2 immunohistochemistry for breast cancer cell blocks can be used in the same way as that used for histological specimens.
abstract: BACKGROUND
  Human epidermal growth factor receptor 2 (HER2) testing of samples from recurrent or metastatic breast cancer is recommended by the 2013 update of the American Society of Clinical Oncology/College of American Pathologists guidelines. Although cytological analysis can be applied to several types of metastatic lesions, the practical method for HER2 testing of cytological specimens is yet to be resolved. We conducted immunohistochemical (IHC) staining for HER2 in breast cancer cell blocks (CBs) and compared the results with those from the corresponding histological specimens. In cases of discrepancy between the two types of specimen, the bright-field HER2 dual in situ hybridization (DISH) assay was performed.
  
  
  METHODS
  CBs were prepared from 54 surgically excised breast cancers. The cells were fixed in 10% buffered formalin and embedded in paraffin. A Ventana BenchMark ULTRA (Roche Diagnostics) with anti-HER-2/neu (4B5) rabbit monoclonal primary antibody and INFORM HER2/neu Dual ISH DNA Probe Cocktail was used for the assays.
  
  
  RESULTS
  Successful results were obtained in 52 of 54 CBs. Forty cases showed agreement between CBs and the histological specimens. No discrepancy was observed between the two types of specimens in cases where HER2 expression was positive. IHC results of CB in 12 discrepant cases were HER2 intermediate or negative. The DISH results of 11 of these cases were negative.
  
  
  CONCLUSIONS
  IHC staining of HER2 for breast cancer CBs can be used in the same way as that used for histological specimens, although the number of equivocal cases in CBs is greater than that in histological specimens. Diagn. Cytopathol. 2016;44:274-279. © 2016 The Authors Diagnostic Cytopathology Published by Wiley Periodicals, Inc.
authors.affiliation: Department of Clinical Laboratory, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Rieko
authors.initials: R
authors.lastname: Nishimura
authors.affiliation: Department of Clinical Laboratory, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Nami
authors.initials: N
authors.lastname: Okamoto
authors.affiliation: Department of Clinical Laboratory, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Satou
authors.affiliation: Department of Clinical Laboratory, National Hospital Organization Shikoku Cancer Center, Matsuyama, Japan.
authors.forename: Kenta
authors.initials: K
authors.lastname: Kojima
authors.forename: Shinichi
authors.initials: S
authors.lastname: Tanaka
mesh_terms: D000911:Antibodies, Monoclonal / Q000737:chemistry; D014408:Biomarkers, Tumor / Q000235:genetics*; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology / Q000601:surgery; D005260:Female; D015870:Gene Expression; D006801:Humans; D007150:Immunohistochemistry / Q000592:standards*; D017404:In Situ Hybridization, Fluorescence; D008867:Microtomy; D009362:Neoplasm Metastasis; D017410:Practice Guidelines as Topic; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D012680:Sensitivity and Specificity; D016610:Tissue Embedding; D016707:Tissue Fixation
chemical_list: D000911:Antibodies, Monoclonal; D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: DISH; HER2; breast cancer; cell block; immunohistochemistry