TTF1 and squamous cell carcinoma: It has been found that cancer cells of PMEC can express CK8/18, CK5/6, CKpan and NapsinA; P63 cancer nuclei were positive, TTF-1 and SMA were negative; Ki-67 positive cells are 2% to 40%, and mucinous cells are positive for AB/PAS staining, and these immunohistochemical findings can help us distinguish it from squamous cell carcinoma, adenosquamous cell carcinoma, and adenoid cystic carcinoma.[9]