Figure 4.

Myeloid-derived lymphatic endothelial cell progenitor (M-LECP)–enriched breast cancer (BC) displays lymphovascular invasion. Human BC specimens were costained for lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1; red) and markers of tumor cells (green). In M-LECP–enriched tumors, various stages of lymphovascular invasion were observed. Examples of selected striking images include the following: attachment of tumor cells to the basal side of the LYVE-1⁺ vascular wall and local degradation of the vascular structure (A), penetration of the tumor cluster identified by anticytokeratin antibody through the LYVE-1–positive monolayer toward the lumen of the vessel (B), and a growing colony of cytokeratin-positive tumor cells inside the lumen of a LYVE-1⁺ vessel (C). Nuclei in merged images are identified by Hoechst stain. White arrowheads indicate tumor cells that have invaded into lymphatic vessels. Scale bar = 20 μm. Original magnification: ×600 (A); ×400 (B and C).