Synchronous/Mixed Ductal and Lobular Carcinomas of the Breast: Further Support of the Precursor Nature of Lobular Neoplasia and Its Marker Status for Low Grade Breast Carcinogenesis.
Fouad I Boulos, Faysal A Fedda, Shant Ayanian, Ghazi Zaatari. American University of Beirut Medical Center, Lebanon
Background: Synchronous/Mixed ductal and lobular carcinomas of the breast are rare, accounting for less than 5% of all female breast cancers. Their histologic features and associations have seldom been described, and their general preneoplastic environment has not been adequately addressed. The purpose of this study is to describe those co-incidental tumors and their directly and indirectly associated precursor lesions, to better understand the neoplastic processes leading to their occurrence.
Design: A search of the Pathology files of the American University of Beirut identified 18 out of 2476 cases that have unequivocal patterns of invasive ductal (IDC) and invasive lobular (ILC) carcinoma. These were assessed for grade, stage, presence of flat epithelial atypia, atypical hyperplasia, in-situ ductal (DCIS) and lobular (LCIS) carcinoma, hormone receptor (ER and PR) status, Her2/neu overexpression, and E-cadherin positivity.
Results: The patients' average age was 49.6 years. Sixteen had their tumors in one breast and 2 in both breasts. The ductal and lobular components were separate in six tumors (6/18), contiguous in two (2/18), and mixed in seven (7/18). The distinct ductal and lobular phenotypes were confirmed histologically, and in 17/18 cases by respective E-cadherin positivity and negativity. The ductal component was of grade 1 in nine cases, grade 2 in seven, and grade 3 in two. DCIS was present in 14/18 cases, while LCIS was present in 15/18 cases. Both were simultaneously present in 12/18 cases. Thirteen IDC were intimately related to DCIS while sixteen ILC were intimately related to LCIS. Estrogen Receptor was positive in all tested tumors (17/18), while Her2/neu was overexpressed in one. Lymph nodes were available in 11/18 cases, and 4/11 were involved. Two cases had mixed ductal and lobular nodal disease with the predominant type mirroring the dominant type in the breast, one had pure lobular, and one pure ductal metastasis.
Conclusions: Our findings reinforce the precursor nature of DCIS and LCIS in breast carcinogenesis, in view of the initimate localization of the in-situ and distinct corresponding invasive components in synchronous/mixed tumors. Also, the predominance of low grade IDC in our cases (50%) as opposed to what is reported in the literature, suggests that the presence of lobular neoplasia favors the development of lower grade invasive ductal carcinomas.
Tuesday, March 1, 2011 9:30 AM
Poster Session III # 29, Tuesday Morning