title: Expression of CK19 in invasive breast carcinomas of special histological types: implications for the use of one-step nucleic acid amplification.
abstract: BACKGROUND
  The sentinel lymph node (SLN) is the first lymph node to receive the lymphatic drainage of a primary tumour; based on the knowledge that CK19 is positive in more than 95% of breast carcinomas, a molecular method for intraoperative diagnosis of SLN metastases (the one-step nucleic acid amplification (OSNA) assay) was developed.
  
  
  OBJECTIVE
  To evaluate CK19 immunoreactivity in a series of special histological types of breast carcinoma in order to verify whether the OSNA assay can be used in all breast cancer cases independently of the histological type.
  
  
  METHODS
  116 samples of invasive breast carcinomas of special type were investigated for CK19 immunoreactivity in tissue microarrays (TMA); negative cases were evaluated in the entire tissue tumour tissue.
  
  
  RESULTS
  Of the 116 cases, 88.9% were positive CK19. Micropapillary and apocrine carcinomas were all positive for CK19 in TMAs. The tubular (93%), mucinous (86%), medullary typical and atypical (84%), mixed carcinomas (83%) increased the rate of positivity for this marker to 100% after repeating the immunostain in whole tissue of negative TMA cases, because the expression of those cases was focal.
  
  
  CONCLUSIONS
  Most breast cancer cases were positive for CK19, independent of the histological type; therefore the OSNA assay can be used in all breast cancer cases with a potential low rate of false negative for CK19 detection of micrometastasis. There is an important variation between the positivity assessed on TMAs and the entire tissue; these findings can be clinically relevant because in some cases CK19 is evaluated on core-needle biopsy prior to surgery.
authors.affiliation: Instituto de Patologia de Campinas, Campinas, São Paulo, Brazil.
authors.forename: César A
authors.initials: CA
authors.lastname: Alvarenga
authors.forename: Paula I
authors.initials: PI
authors.lastname: Paravidino
authors.forename: Marcelo
authors.initials: M
authors.lastname: Alvarenga
authors.forename: Rozany
authors.initials: R
authors.lastname: Dufloth
authors.forename: Madalena
authors.initials: M
authors.lastname: Gomes
authors.forename: Luiz C
authors.initials: LC
authors.lastname: Zeferino
authors.forename: Fernando
authors.initials: F
authors.lastname: Schmitt
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002277:Carcinoma / Q000378:metabolism* / Q000473:pathology*; D005260:Female; D006801:Humans; D053539:Keratin-19 / Q000032:analysis*; D009361:Neoplasm Invasiveness; D021141:Nucleic Acid Amplification Techniques; D021701:Sentinel Lymph Node Biopsy; D046888:Tissue Array Analysis
chemical_list: D014408:Biomarkers, Tumor; D053539:Keratin-19