Fig. 3

Histopathological and immunohistochemical findings of POT. a Hematoxylin and eosin staining of POT. b CK19 was positive only in columnar epithelium. c Vimentin was positive throughout the tumor tissue (strongly positive in epithelial layers and moderately positive in mesenchymal tumor cells). d Ectomesenchymal cells were negative for α-SMA. e Ectomesenchymal cells were negative for S-100 protein. f Ki67 labeling index was basically lower than 2%. (magnification, × 100)