Immunohistochemical staining of E-cadherin and its binding complex in invasive lobular carcinoma. Lobular carcinoma in situ (LCIS) and invasive lobular carcinoma (ILC); note invasive neoplastic cells of ILC (arrows) growing in a targetoid fashion around the in situ component. (A) E-cadherin and (B) β-catenin staining is negative in both LCIS and ILC, although positive staining is observed in the myoepithelial cells surrounding the LCIS. (C) Pagetoid spread (asterisks) is also observed in this case, whereby the neoplastic cells (negative for E-cadherin) are growing and invading between the luminal and myoepithelial cells of a normal ductal structure). (D) In the absence of E-cadherin, there is a strong re-localisation of p120-catenin to the cytoplasm of neoplastic cells in LCIS and ILC.