Figure 3. Histopathological exam. (A) Mucosis fragments covered with epithelial keratinized and non-keratinized tissue. Epithelial papillary projections through the adjacent stroma that confers an inverted architecture in relation to the neoplastic epithelium and the presence of continuous cells nests with the epithelial surface (arrows). Scale bar: 200 µm. (B) Stratified epithelial tissue and conjunctive tissue loosely ordered with an inflammatory lymphoplasmacytic infiltrated (asterisk). Scale bar: 200 µm. (C) Stratified squamous keratinized epithelial tissue showing papillary projections of many sizes (arrow). In other area, was observed respiratory epithelium (arrowhead). (D) Presence of hyperchromatic cells, with voluminous nucleus in the epithelium basal and parabasal and koilocytes in the superficial layers (arrows). Scale bar: 20 µm.