Research ArticlesA New Rabbit Monoclonal E-Cadherin Antibody [EP700Y] Shows Higher Sensitivity Than Mouse Monoclonal E-Cadherin [HECD-1] Antibody in Breast Ductal Carcinomas and Does Not Stain Breast Lobular CarcinomasHoang, Laura L. PhD*; Tang, Ping MD, PhD†; Hicks, David G. MD†; Chen, Huijiao MD†; Yang, Qi BS†; Haas, Thomas S. DO, FCAP‡; Bremer, Ryan E. PhD*; Tacha, David PhD*Author Information *Department of Research and Development, Biocare Medical LLC, Concord, CA †University of Rochester Medical Center, Rochester, NY ‡Mercy Health System, Janesville, WI The authors declare no conflict of interest. Reprints: David Tacha, PhD, Department of Research and Development, Biocare Medical LLC, 4040 Pike Lane, Concord, CA 94520 (e-mail: [email protected]). Received June 13, 2013 Accepted July 12, 2013 Applied Immunohistochemistry & Molecular Morphology: September 2014 - Volume 22 - Issue 8 - p 606-612 doi: 10.1097/PAI.0b013e3182a4edef Buy Metrics Abstract Immunohistochemical studies have shown E-cadherin to be expressed in breast carcinomas showing a ductal histology, with a corresponding loss of expression in tumors with a lobular histology. As a result, mouse monoclonal anti-E-cadherin [HECD-1] has been used by pathologists to differentiate between ductal and lobular carcinomas, with currently published sensitivity and specificity rates of approximately 90%. Rabbit monoclonal antibodies may combine the best properties of both mouse monoclonal antibodies and rabbit antisera. Therefore, this study compares the staining sensitivity and specificity of a new rabbit monoclonal E-cadherin and the standard mouse monoclonal E-cadherin [HECD-1] in breast ductal carcinomas, and evaluates a cocktail of rabbit monoclonal E-cadherin and p120 catenin in the discrimination of ductal from lobular carcinomas. The rabbit E-cadherin showed sharper staining and increased sensitivity (80/81, 99%) than the mouse E-cadherin (75/81, 93%). The rabbit E-cadherin achieved a score of 3+ in 85.2% (69/81) of cases as compared with a 3+ in only 21.0% (17/81) of cases stained with mouse E-cadherin. All lobular carcinomas (n=37) were confirmed by the absence of E-cadherin and the diffuse cytoplasmic expression of p120 catenin. Although both the single mouse E-cadherin and dual stain can differentiate ductal from lobular lesions, the dual stain is helpful in challenging cases because of its bright pink p120 catenin and dark brown rabbit E-cadherin staining. The highly sensitive rabbit E-cadherin antibody is the preferred antibody for evaluating ductal carcinomas and for distinguishing ductal versus lobular lesions, and the dual stain was superior to the single E-cadherin stain. © 2014 Lippincott Williams & Wilkins, Inc.