Immunohistochemical studies of lymphatic vessels have been limited by a lack of specific markers. Recently, the novel D2-40 antibody, which selectively marks endothelium of lymphatic vessels, was released. The aim of our study is to compare lymphatic and blood vessel invasion detected by hematoxylin and eosin (H&E) versus that detected by immunohistochemistry, relating them with morphologic and molecular prognostic factors.

We selected 123 cases of invasive mammary carcinomas stratified into three subgroups according to axillary lymph node status: macrometastases, micrometastases, and lymph node negative. Lymphatic (LVI) and blood (BVI) vessel invasion were evaluated by H&E and immunohistochemistry using the D2-40 and CD31 antibodies, and related to histologic tumor type and grade, estrogen and progesterone receptors, E-cadherin, Ki67, p53, and Her2/neu expression.

LVI was detected in H&E-stained sections in 17/123 cases (13.8%), and in D2-40 sections in 35/123 cases (28.5%) (Kappa = 0.433). BVI was detected in H&E-stained sections in 5/123 cases (4.1%), and in CD31 stained sections in 19/123 cases (15.4%) (Kappa = 0.198). LVI is positively related to higher histologic grade (p = 0.013), higher Ki67 expression (p = 0.00013), and to the presence of macrometastases (p = 0.002), and inversely related to estrogen (p = 0.0016) and progesterone (p = 0.00017) receptors expression.

D2-40 is a reliable marker of lymphatic vessels and is a useful tool for lymphatic emboli identification in immunostained sections of breast carcinomas with higher identification rates than H&E. Lymphatic vessel invasion was related to other features (high combined histologic grade, high Ki67 score, negative hormone receptors expression) associated with worse prognosis, probable reflecting a potential for lymphatic metastatic spread and aggressive behavior.