[255] Transmembrane Protein E-Cadherin May Not Be Necessary for Duct Formation in Breast Carcinomas

J Liu, A Heimann, M Singh, Z Schreiber, Y Hu, B O'Hea, C Tornos. Stony Brook University Medical Center, Stony Brook, NY

Background: Two major forms of breast carcinomas are invasive ductal (IDC) and invasive lobular (ILC) carcinomas. IDC usually show duct formation. ILC typically show single file growth pattern and lack of ductal differentiation. E-cadherin, a transmembrane protein, has been shown to be a useful aid for differentiating between IDC and ILC. E-cadherin is usually negative in ILC but positive in IDC with a strong membranous staining pattern by immunohistology. Thus, E-cadherin protein is thought to play a role in forming the characteristic histologic morphology of breast carcinomas. While studying invasive mammary carcinomas with mixed invasive ductal and lobular features, we have encountered four cases of invasive carcinomas with E-cadherin negative, duct forming areas.
Design: Invasive mammary carcinomas with mixed ductal and lobular features based on histomorphology were identified in our department file. E-cadherin stain was performed either during the initial pathologic examination or during the current study.
Results: We identified 51 cases of invasive mammary carcinomas with mixed ductal and lobular features based on histomorphology in our department file from 2005 to 2009. E-cadherin stain showed that 8 cases are negative for E-cadherin and therefore the 8 cases were re-classified as ILC. These 8 cases showed tumor cells predominately growing in single file or cords like pattern. Interestingly, we also noticed that tumor cells focally formed ducts in 4 of the 8 cases (well-formed ducts in 1 case; poorly formed ducts in three). In spite of the duct formation, the E-cadherin negativity and dominant single file or cords like growth pattern favor a diagnosis of ILC.
Conclusions: In a small proportion of ILC, E-cadherin negative tumor cells may form duct like structures. Thus, E-cadherin protein may not be necessary for duct formation in breast cancers. The finding may facilitate further study on the biological role of adhesion and cell polarity related molecules in breast cancers.
Category: Breast

Tuesday, March 23, 2010 9:30 AM

Poster Session III # 41, Tuesday Morning

 

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