Fig. 6

Histological examination of biopsy. a An image showing atypical epithelium proliferating and forming small and large foci × 40. The tumor is partially exposed and ulcerated, and areas of continuity with the coated epithelium can be observed. b The lesions show a keratinizing tendency and some appear fenestrated (× 200). Tumor cells showing strong atypia, including nuclear staining and enlargement, discrepancy in nuclear size, and irregularity in nuclear shape