Immunostains of PMEC.

<p>(A) Muc5AC highlighted the partial mucous cells within the tumors (x150). (B) p63 was positive in both intermediate and epidermoid cells (x150). (C) TTF-1 was negative in all three cells (x150). (D) ALK was negative (x150). (E) Ki-67 was positive in the nucleus in a low-grade tumor, and the labeling index is 2% (x150). (F) Ki-67 was positive in the nucleus in the dedifferentiation area, and the labeling index is about80% (x150).