Abstract
BackgroundE-cadherin, a cell surface protein involved in cell adhesion, is present in normal breast epithelium, benign breast lesions, and in breast carcinoma. Alterations in the gene CDH1 on chromosome 16q22 are associated with changes in E-cadherin protein expression and function. Inactivation of E-cadherin in lobular carcinomas and certain diffuse gastric carcinomas may play a role in the dispersed, discohesive "single cell" growth patterns seen in these tumors. The molecular "signature" of mammary lobular carcinomas is the loss of E-cadherin protein expression as evidenced by immunohistochemistry, whereas ductal carcinomas are typically E-cadherin positive.Patients and methodsWe report on E-cadherin immunostaining patterns in five cases of invasive mammary carcinomaResultsThese were five exceptional instances in which the E-cadherin immunophenotype did not correspond to the apparent histologic classification of the lesion. These cases which are exceedingly rare in our experience are the subject of this report.ConclusionFindings such as those illustrated in this study occur in virtually all biologic phenomena and they do not invalidate the very high degree of correlation between the expression of E-cadherin and the classification of breast carcinomas as ductal or lobular type on the basis of conventional histologic criteria.
Highlights
E-cadherin, a cell surface protein involved in cell adhesion, is present in normal breast epithelium, benign breast lesions, and in breast carcinoma
Well-formed ducts comprised greater than 90% of the invasive carcinoma (Figure 1A)
A single axillary lymph node was involved by metastatic carcinoma composed of tumor cells in a diffuse, discohesive pattern characteristic of metastatic lobular carcinoma
Summary
E-cadherin, a cell surface protein involved in cell adhesion, is present in normal breast epithelium, benign breast lesions, and in breast carcinoma. The molecular "signature" of mammary lobular carcinomas is the loss of E-cadherin protein expression as evidenced by immunohistochemistry, whereas ductal carcinomas are typically E-cadherin positive. The utility of the E-cadherin immunohistochemical stain to distinguish between lobular and ductal carcinomas that are difficult to classify by morphologic features alone has been well-documented in recent years [1,2,3,4,5,6,7,8]. We report 5 cases of invasive mammary carcinoma with a striking discordance between the structural phenotype of the lesion in hematoxylin and eosin sections and immunohistochemical staining pattern for E-cadherin, a phenomenon we have termed as "aberrant".
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