[193] Pleomorphic Lobular Carcinoma In Situ of the Breast: Clinicopathological Review of 57 Cases and a Proposed New Histopathologic Classification

Thaer Khoury, Rouzan Karabakhtsian, Li Yan, Susanna Syriac, Song Liu, Mohamed M Desouki. Roswell Park Cancer Institute, Buffalo, NY; University of Kentucky, Lexington, KY; Vanderbilt University, Nashville, TN

Background: Pleomorphic lobular carcinoma in situ (PLCIS) of the breast is a distinctive entity, that its definition and management is unclear. The purpose of this study is to review a large number of cases and propose a new histopathologic classification according to the clinical outcome.
Design: Cases of PLCIS (n=57) from three academic institutions along with cases of classic LCIS (CLCIS) (n=39) and DCIS (n=615) over 12 year-period were reviewed. The clinical, radiological and pathological findings were recorded. Immunohistochemical markers (ER, PR, HER2, Ki-67, p53, GCDFP-15, mammaglobin, CK7, CK17, CK5/6, EGFR, and BCL-2) were performed on 20 PLCIS cases. PLCIS cases were classified based on the histologic pattern into conventional pleomorphic (>10% of cells have pleomorphism), necrotic (comedo type), macroacinic, and mixed subtypes. PLCIS cases are also classified based on the cell type into apocrine, non-apocrine, signet ring, histiocytic and mixed subtypes.
Results: For PLCIS, 47 (82.5%) cases had mixed histologic pattern and 28 (49.1%) had mixed cell type. Seven of 57 (12.3%) PLCIS cases had tumor recurrence. All recurred cases had mixed histologic pattern. The cell type was apocrine (n=1), non-apocrine (n=2) and mixed (n=4) in cases with local recurrence. Local recurrence was more common in younger patients (mean age 53-years vs. 60-years) and in cases with positive margin for CLCIS (p=0.02 and p=0.01, respectively). Both PLCIS and DCIS more commonly involved postmenopausal patients when compared to CLCIS (p<0.0001). While PLCIS was more likely to develop local recurrence compared to grade I- and grade II-DCIS (p=0.06 and 0.04, respectively), it had similar local recurrence rate to grade III-DCIS. All patients who developed local recurrence were not treated with radiation therapy. ER, PR, HER2, GCDFP-15, mammaglobin, BCL-2, CK7, were positive in 70%, 65%, 30%, 75%, 55%, 90%, and 100%, respectively. CK17, CK5/6, EGFR tested negative in all PLCIS cases. The median and range for Ki-67 and p53 was 5% (2%-40%) and 20 (0 to 240), respectively.
Conclusions: The proposed classification of PLCIS is based on the histologic pattern and predominant cell type. This classification could be useful to better recognize PLCIS. This study is the first to provide an insight to the clinical behavior of PLCIS and therefore to provide the patient with the proper management.
Category: Breast

Monday, March 4, 2013 2:15 PM

Proffered Papers: Section B, Monday Afternoon


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