Fig. 2.

Histologic manifestation. a Thickened neoplastic spinous cell layer. b Local keratosis presenting the appearance of church spire. c Elongated lamina propria papilla upward to the surface layer. d Tumor cells with double or more nucleoli in the basal region, and tumor cells breaks through the basement barrier and invades superficial lamina propria. e IPCLs observed by microscopy (right) and endoscopy (left).