Lymphatic and capillary invasion patterns in triple negative breast cancer

Triple negative breast cancer (TNBC) comprises approximately 15 to 20 per cent of all breast cancer cases. Many studies have detected less lymph node metastasis in TNBC than sporadic breast cancers. In this study, we studied capillary and lymphatic invasion in tumors of patients with TNBC. To differentiate the capillary invasion and lymphovascular invasion. We used the Antihuman CD34 and antihuman D2-40 antibodies. Antihuman CD34 antibodies stain the blood vessels and lymphatics. However, antihuman D2-40 antibodies stain lymphatics specifically. Two experienced pathologists blinded to clinical data evaluated capillary and lymphatic invasion existence in 39 TNBC patients' tumor samples. Tumor samples were immunohistochemically stained with CD34 (endothelial cell marker) and D2-40 (podoplanin, a membrane protein, specific for lymphatic endothelium). The CD34-positive samples were categorized into two groups depending on their reaction with D2-40: lymphatic (D2-40-positive) and capillary (D2-40-negative) invasion. We have detected vascular invasion in 15 of 39 samples (38.5%) with CD34. Among those, capillary invasion was found in 14 (35.9%) and lymphatic invasion in three (7.7%) and both in two (5.1%) tumors. We did not find any significant correlation among capillary invasion, lymphatic invasion, vascular invasion, tumor grade, menopause status, history of cancer, and TNM. Capillary invasion is more commonly observed than lymphatic invasion in patients with TNBC. This finding supports the fact that more hematogenous metastasis (spreading) and less lymph node metastasis are seen in patients with TNBC.