Invasive lobular carcinoma of the breast: role of endothelial lymphatic marker D2-40.

Lymphovascular invasion (LVI) of breast cancer is an independent adverse prognosticator that is associated with increased regional and distant tumor recurrence. LVI is infrequently encountered in invasive lobular carcinoma when compared to invasive ductal carcinoma. We employed D2-40 antibody, a novel marker for lymphatic endothelial cells, in an attempt to enhance the detection of LVI in invasive lobular carcinomas. We identified 78 patients with invasive lobular carcinoma with known axillary status, who were studied between 2003 and 2006. D2-40 antibody was applied to one representative paraffin block from each case and the results were compared to LVI on routine histology. LVI was identified in 12 (15%) and 19 (24%) cases by routine histology and D2-40 antibody, respectively. Eleven of 12 patients (92%) with LVI identified by routine histology had axillary nodal metastasis compared to 14 of 19 patients (74%) with LVI identified by D2-40 antibody. LVI was missed by routine histology in 8 cases (10%). D2-40 antibody enhanced the identification of LVI by 9% in node negative patients. D2-40 antibody increased the identification of LVI by 12% in classic invasive lobular carcinoma. In conclusion, D2-40 antibody staining may be useful as an adjunct in detecting LVI in invasive lobular carcinoma, especially in node-negative patients with the classic variant of invasive lobular carcinoma.