Fig. 4

Immunohistochemical staining results. (A) The SM cells were diffusely positive for CK5/6 (magnification ×20). (B) Immunostaining of p40 in the areas of squamous metaplasia were negative (magnification ×100). (C) The SM cells were negative for p63 (magnification ×100) (D) The SM cells were uniformly weak positive for CDX2, while neoplastic glands and normal mucosal glands were strongly positive (magnification ×40). (E) The nuclei, cytoplasm, and membrane showed diffuse and strong positivity for β-catenin (magnification ×400). (F) Ki67 staining showed a very low cell proliferation index whether in the solid nests or cribriform-morular-like structure of the SM (magnification ×100)