Pleomorphic lobular carcinoma: a distinctive clinical and molecular breast cancer type

Abstract

Pleomorphic lobular carcinoma (PLC) is an aggressive variant of invasive lobular carcinoma. The aim of this study was to redefine PLC in terms of molecular classification. Cases of PLC were selected between 1995 and 2010. Key clinicopathological features were recorded for most of the patients. A panel of immunohistochemical stains including E-cadherin, oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), cytokeratin (CK)5/6, CK14, CK17, anti-cytokeratin (CAM) 5.2, CD117, vimentin, epidermal growth factor receptor (EGFR), p53 and gross cystic disease fluid protein-15 (GCDFP-15) were performed. HER2 test by fluorescence in-situ hybridization (FISH) was also performed. The log-rank test was used for statistical analyses. Forty cases fulfilled the criteria for PLC (26 with available tissue). The median age was 61 years and median tumour size was 2.0 cm. There were five of 38 (13.2%) triple-negative cases. The basal type was seen in one of 25 cases (4%), which had a triple-negative phenotype. HER2 was amplified in 14 of 38 cases (35%). Older patients and negative hormonal receptor status correlated significantly with worse clinical outcome (P < 0.03). The 5-year recurrence-free and overall survival was 54.9% and 76.2%, respectively. Pleomorphic lobular carcinoma is a distinctive breast cancer subtype. It has hybrid clinicopathological characteristics of ductal and lobular carcinoma.