Figure 4.

Histopathologic image of the resected specimen. In the upper image, tumor cells are seen invading the lamina propria in the protruding component by the black box. Intraepithelial cancer is observed around the protruding component (hematoxylin and eosin [H&E], original magnification, loupe image). In the lower left image, the black box area of the upper image is enlarged. Downward growth of squamous cell carcinoma can be seen (H&E, original magnification ×100). In the lower right image, the dotted box area of the lower left image is enlarged. It can be confirmed as well-differentiated squamous cell carcinoma with cancer pearl formation (H&E, original magnification ×200).