Pathological findings.

<p>A: Light microscopy showed the tumor covered with pseudostratified, ciliated, columnar epithelium or stratified squamous epithelium with edematous stroma, and many infiltrating inflammatory cells (hematoxylin and eosin staining; original magnification, ×100). B: Proliferation of thin-walled vascular channels. Separated blood vessels exhibited concentric accumulation of amorphous material (hematoxylin and eosin staining; original magnification, ×100).