Invasive Pleomorphic Lobular Carcinoma of the Breast: Clinicopathologic Characteristics and Prognosis Compared with Invasive Ductal Carcinoma

Purpose: Invasive pleomorphic lobular carcinoma (IPLC) is a very rare and distinct morphological variant of invasive lobular carcinoma (ILC), characterized by nuclear atypia and pleomorphism contrasted with the cytologic uniformity of ILC. This study evaluated clinicopathologic characteristics and prognosis of IPLC compared with invasive ductal carcinoma (IDC). Methods: We retrospectively reviewed the medical records of 35 patients with IPLC and 6,184 patients with IDC, not otherwise specified. We compared the clinicopathologic characteristics, relapse-free survival (RFS) and disease specific survival (DSS) of patients who were surgically treated between January 1997 and December 2010. Results: Patients with IPLC presented at an older age with larger tumor size, worse histologic grade, higher rates of N3 stage, more multifocal/multicentric tumors, and more nipple-areolar complex involvement than those of patients with IDC. During the follow-up period, the IPLC group experienced five cases (14.3%) of disease recurrence and three cases (8.6%) of disease specific mortality compared with 637 cases (10.4%) of recurrence and 333 cases (5.4%) of disease specific mortality in the IDC group. Univariate analysis using the Kaplan-Meier method revealed that the IPLC group showed a significantly poorer prognosis than that of the IDC group (RFS, p=0.008; DSS, p<0.001). However, after adjusting for clinicopathologic factors, a multivariate analysis showed no statistical differences in RFS(p=0.396) and DSS (p=0.168)between the IPLC and the IDC groups. Conclusion: Our data suggest that patients with IPLC present with poor prognostic factors such as large tumor size, poor histologic grade and advanced stage at diagnosis. These aggressive clinicopathologic characteristics may result in poor clinical outcomes. Although our study could not link IPLC histology to poor prognosis, considering the aggressive characteristics of IPLC, early detection and considerate treatment, including proper surgical and adjuvant intervention, could be helpful for disease progression and survival.