Clinicopathologic and Genomic Characterization of Solid Papillary Breast Carcinoma (SPC)
Carey Eberle, Mark Magbanua, Eduardo Sosa, James Grenert, Joseph T Rabban, Charles Zaloudek, Yunn-Yi Chen. University of California, San Francisco, San Francisco, CA
Background: SPC can be challenging to diagnose and manage because myoepithelial cells (MEC) may be absent in morphologically well-circumscribed tumors. In this study, we correlate the clinical features, biomarker profiles and genomic alterations of SPC, emphasizing cases that are difficult to classify.
Design: 56 SPC were identified from 2001-2011. The cases were classified based on growth pattern and MEC expression (Table). The clinical features were reviewed. Conventional carcinoma, when present, was noted. Biomarker expression was examined using immunostains for ER, PR, HER2, and neuroendocrine (NE) markers. Genome-wide alterations were analyzed by array-based comparative genomic hybridization (aCGH) on selected cases.
Results: 50/56 cases could be classified with certainty, but 6 had discrepant growth pattern versus MEC expression (group D). In follow-up (0.1-10.3 y), LN metastasis was not identified in the cases with indeterminate classification. Among the 56 SPC, 95% were low to intermediate histologic grade. 96% were ER/PR positive and none overexpressed HER2. aCGH evaluated on 4 SPC (2 in group B, 1 each in C, E) showed a similar genomic profile with recurrent changes (75-100%) including gains of 1q, 5q & 10q, and losses of 2p, 8q, 13q, 14q, 15q & 16q. 2 of 31 patients with LN sampling had metastasis, both in patients with an invasive SPC component; metastases displayed SPC morphology. One patient developed recurrence. No patient died from SPC.
Conclusions: We are unable to identify specific features to better classify the indeterminate SPC. Because no LN metastasis is observed in this group, the question remains whether these are invasive tumors or not. Preliminary aCGH study suggests characteristic genomic alterations in invasive SPC. Comparison of aCGH in group D to other groups may help further classify indeterminate cases and is in progress.
|All patients (n=56)||A: in situ SPC only (n=5)||B: in situ + inv SPC (n=18)||C: in situ SPC + IDC (n=12)||D: Indeterminate SPC (n=6)||E: Invasive SPC (n=15)|
|Bloody nipple discharge*||17%||50%||20%||30%||0%||0%|