E-cadherin immunohistochemistry in breast pathology: uses and pitfalls.

E-cadherin immunohistochemistry is used commonly in surgical pathology practice to help distinguish lobular carcinoma in situ from ductal carcinoma in situ and invasive lobular carcinoma from invasive ductal carcinoma in histologically problematic or indeterminate cases. However, the interpretation of E-cadherin immunostains is not always straightforward. Failure to recognize the pitfalls and limitations of E-cadherin immunostains can lead to an erroneous diagnosis which may result in inappropriate patient management, particularly for patients with in-situ lesions. In this paper we review the uses and, particularly, the pitfalls in the interpretation of E-cadherin immunostains in distinguishing lobular from ductal lesions of the breast.