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J Clin Pathol 64:493-497 doi:10.1136/jcp.2011.089862
  • Original article

Expression of CK19 in invasive breast carcinomas of special histological types: implications for the use of one-step nucleic acid amplification

  1. Fernando Schmitt2,5
  1. 1Instituto de Patologia de Campinas, Campinas, São Paulo, Brazil
  2. 2Institute of Molecular Pathology and Immunology of the University of Porto (IPATIMUP), Porto, Portugal
  3. 3Department of Gynecology and Obstetrics, State University of Campinas (UNICAMP), Campinas, São Paulo, Brazil
  4. 4PUC-Campinas University, Campinas, São Paulo, Brazil
  5. 5Medical Faculty of Porto University, Porto, Portugal
  1. Correspondence to Fernando Schmitt, IPATIMUP, Rua Dr Roberto Frias s/n, 4200-465 Porto, Portugal; fschmitt{at}ipatimup.pt
  • Accepted 16 February 2011
  • Published Online First 22 March 2011

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.

Aims 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.

Conclusion 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.

Footnotes

  • Funding Supported by Fundação de Apoio à Pesquisa do Estado de São Paulo (FAPESP, grant number 2010/00815-6), CAPES, Ministry of Education, Brazil (PhD grant 3420-09-04 to CAA) and Fundação para a Ciência e Tecnologia, Portugal (PIC/IC/83264/2007 to MG).

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.