Clinicopathologic and biomarker analysis of invasive pleomorphic lobular carcinoma as compared with invasive classic lobular carcinoma: an experience in our institution and review of the literature.

Pleomorphic lobular carcinoma (PLC) is a distinct morphological variant of invasive lobular carcinoma (ILC). Although PLC retains the distinctive loosely cohesive and single-file growth pattern of ILC, it has specific distinguishable characteristics, including enlarged nuclei with greater nuclear irregularity, increased hyperchromasia, prominent nucleoli, increased mitotic activity, and abundant eosinophilic cytoplasm. We compared the clinicopathologic features and biomarker expression of PLC and ILC. Fifty-eight cases of classic ILC (5.3%) and 7 cases of PLC (0.6%) were identified from our file between January 2002 and December 2010. Histopathologic data and tumor biomarkers were recorded. Clinical follow-up information (3-93 months; median, 29 months) for distant metastasis and survival was also gathered. Fisher exact test was used, and results were considered statistically significant if P value is less than .05. Our results showed that compared with classic ILC, PLC was more frequently grade III (P < .01), estrogen receptor negative (P < .001), and has Ki-67 greater than 10% (P < .002). In conclusion, PLC is more frequently higher grade and may exhibit an adverse biomarker profile (negative estrogen receptor and high Ki-67) as compared with classic ILC. However, no significant differences were found between PLC and classic ILC for axillary lymph node/distant metastases and survival.