Vascular invasion in squamous cell carcinomas of human oral mucosa

The process of vascular invasion of human oral squamous cell carcinomas was histologically and immunohistochemically studied in surgical and autopsy specimens. Hematoxylin-eosin, Masson's trichrome, and immunohistochemical stainings for Ulex europaeus I lectin binding, CD31, and type IV collagen were done to differentiate lymphatic and blood vessels and to demonstrate basement membranes in vascular walls and around carcinoma cell nests was observed. With growth of tumor, there was mechanical disruption of vascular walls and endothelial cells by carcinoma cell nests. After disrupting vascular walls, they invaded into the lumen as clusters, not as single cells. At the blood vessel invasion sites, inflammatory reactions were seen around carcinoma cell nests inside as well as outside lumina with microthrombotic reactions due to endothelial injury. At the lymphatic invasion sites, carcinoma cell nests maintained their volume inside the lumen and the cells adhered tightly to each other, and inflammatory reaction was scarcely seen. These findings showed that mechanical pressure has an important role in the vascular invasion of human oral squamous cell carcinoma.