[294] Mucinous Breast Carcinoma Associated with Lobular Neoplasia: A Potentially Characteristic Subset with Abnormality of Cell Adhesion and Polarity Molecules, and Lack in Neuroendocrine Differentiation

Hitoshi Tsuda, Masayuki Yoshida, Yuka Katsurada, Akiko M Maeshima. National Cancer Center Hospital, Chuo-ku, Tokyo, Japan

Background: Mucinous carcinoma (MUC) accounts for about 2% of all breast carcinomas, whereas lobular neoplasia (lobular carcinoma in situ/atypical lobular hyperplasia) is found in 0.5-4% of otherwise benign breast biopsies. The intraductal component of MUC is usually common ductal carcinoma in situ (DCIS), but the component may be endocrine (or solid-papillary) subtype DCIS. Since we have experienced a case of MUC that accompanied with extensive LN component, we had the speculation that a subset of MUC occurs in association with LN and may show unique biological properties.
Design: In surgically resected consecutive 41 cases of MUC, the presence of LN component or the coexistence of LN foci around the MUC lesion was examined histopathologically. In the MUC and LN components, the expressions of E-cadherin, β-catenin, chromogranin A, and synaptophysin were immunohistochemically examined. The correlation between endocrine differentiation and coexistence with LN was also analyzed in these MUC cases.
Results: LN was detected in the background of MUC in 12 cases (29%), varying 1 to 85 mm in diameter: 6 with LN only and other 6 with both LN and DCIS components. In 11 of these 12 LNs, both E-cadherin and β-catenin were negative. In MUC component, E-cadherin and β-catenin expressions were abnormal (heterogeneous or markedly decreased) in 3 (25%) and 8 (67%) of 12 cases of MUC with LN component, respectively, whereas they were abnormal in only 2 (7.6%) and 5 (19%) of 26 MUCs without LN component, respectively. The percentage of neuroendocrine feature in MUC was not different between MUCs with and without LN component (6/13, 46% and 14/27, 52%), but in 6 cases of MUC with LN without DCIS component, 5 (83%) were negative of neuroendocrine features.
Conclusions: Although it is still undetermined whether there is sequence from LN to MUC or there is a common carcinogenic pathway for LN and MUC, MUC associated with LN had characteristic molecular features including derangement of cell-cell adhesion and cell polarity molecule expressions as well as lack in neuroendocrine differentiation.
Category: Breast

Wednesday, March 6, 2013 9:30 AM

Poster Session V # 42, Wednesday Morning

 

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