Mammary carcinomas including pleomorphic lobular variant: clinicopathological and immunohistochemical study

ABSTRACT

Some mammary carcinomas are uncommon and have poor prognosis. Pleomorphic lobular carcinoma of the breast is one of these types. This variant hinders its correct identification and differentiation from duct carcinoma, particularly the higher histological grade of the latter. E-cadherin-beta catenin complex is a powerful tool for this differentiation. E-cadherin is a transmembrane glycoprotein mediates epithelial cell-to-cell adhesion. Loss of E-cadherin results in disruption of the cellular clusters. Sometimes invasive duct carcinoma demonstrated an invasive lobular growth pattern. Additionally, some variants of invasive lobular carcinoma particularly pleomorphic and tubulolobular types are difficult to be differentiated from invasive duct carcinoma in particular when the latter demonstrated higher histological grades. As these types are differening in their clinicopathological characters, treatment strategy, and prognostic behaviors, so, the differentiation between them is very important. E-cadherin expression can solve this diagnostic dilemma as it expressed strongly in most invasive duct carcinoma and lacked in many lobular neoplasia. The aim of this study is evaluate E-cadherin-beta-catenin expression in invasive duct carcinoma, invasive classic lobular carcinoma, and pleomorphic lobular carcinoma. As sometimes the histologic differentiation between advanced types of invasive duct and lobular carcinomas is so difficult, it is important for this differentiation to be made. In these equivocal cases, Immunohistochemical detection of E-cadherin-beta catenin expression is of useful diagnostic aid. Additionally, to demonstrate the clinicopathological characters of pleomorphic lobular carcinoma. Antibodies to E-cadherin-beta-catenin, and HER-2 neu were used immunohistochemically in 55 cases of mammary carcinomas. These cases included 35 cases [63.6%] invasive duct carcinoma, 6 cases [10.9%] invasive duct carcinoma with lobular features, 9 cases [16.4%] classic invasive lobular carcinoma, 4 cases [7.3%] pleomorphic lobular carcinoma, and one case [1.8%] was tubulolobular carcinoma. As well as antibody against high molecular weight cytokeratin [HMWCK] was included in this study. This series study revealed strong membranous immunostaining for E-cadherin in 32 cases [91.4%] of invasive duct carcinoma. While the remaining 3 cases [8.6%] of were negative. Additionally, all the included 6 cases of invasive duct carcinoma with lobular features were positive for E-cadherin membranous immunostaining. As well as all cases of invasive duct carcinoma showed membranous immunostaining for beta-catenin immunoexpression. In the opposite direction all cases of classic invasive, pleomorphic lobularand the included case of tubulolobular carcinomas were lacked any membranous immunostaining for E-cadherin and beta-catenin immunoexpression. Among invasive duct carcinoma 10 cases [28.6%] revealed HER-2 neu positive immunostaining, while the remaining 25 cases [71.4%] of them lacked HER-2 new immunoreactivity. Among the invasive duct carcinoma with lobular features 2 out of the 6 cases revealed HER-2 neu positive membranous immunoreactivity. In the other hand HER-2 neu reactivity was detected in one case [11.1%] of classic invasive lobular carcinoma, while the remaining 8 cases [87.9%] of them lacked HER-2 neu immunostaining. Two cases [50%] of pleomorphic lobular carcinoma were positive for HER-2 neu immunoexpression, while the other 2 cases [50%] were negative. The included single tubulolobular carcinoma case was negative for HER-2 neu immunoreactivity. Our study demonstrates a strong positive E-cadherin-beta-catenin immunoreactivity in the majority of invasive duct carcinoma. The classic invasive and pleomorphic lobular carcinomas were negative for E-cadherin-beta-catenin immunoexpression. So, E-cadherin-beta-catenin complex is very important immunohistochemical marker for the differentiation between the two common and important types of mammary carcinomas