Histological classification. (A) Representative cases of keratinizing squamous cell carcinoma (KSCC): The tumor was composed entirely of mature squamous cells. (B) Representative cases of nonkeratinizing squamous cell carcinoma (NKSCC): Tumor cells form sheets of nonmaturing cells with pushing borders, only sometimes with peripherally or abruptly keratinizing/maturing focus (Arrow). (C & D) Representative cases of hybrid squamous cell carcinoma (HSCC): Tumor grows in non-maturing cell sheet, but with focal squamous maturation diffusely throughout the tumor. (E) Representative case of basaloid squamous cell carcinoma: Small and densely packed tumor cells and with grow in a lobular configuration. Basaloid SCC (arrows) was seen next to conventional NKSCC (arrow heads). (F) Representative case of lymphoepithelial carcinoma: Tumor cells have syncytial cytoplasm, growing with prominent inflammatory background. (G) Representative case of papillary squamous cell carcinoma: Tumor cells grow in an arborizing papillary fashion. (H) Unclassified squamous cell carcinoma: The tumor cells, showing bizarre nuclei with high nuclear grade, grow monotonously; hence, this could not be classified into any of the above. [A to H, Hematoxylin and eosin staining, with original magnification: x200, x150, x200, x200, x150, x300, x100, x300 , respectively].