Figure 1.

Main immunohistochemical features in ameloblastoma: a. Ameloblastoma showing the nuclei of a few cells of the basal and suprabasal layers positive for Ki-67 (200X), b. Nuclear expression of p53 in AM, positive cells are evident, but the intensity of the staining is weak- arrows (200X), c. p63 immunostaining in ameloblastomas, showing epithelial islands intensely positive mainly in the peripheral cells, but many of the central cells also expressed this marker (200X), d. The central areas of the islands/cords were strongly positive for CK5, while the expression was weaker or negative on the peripheral columnar cells (200X), e. Follicular islands showing stronger expression in the central areas, but the basal layer was also positive. Arrow shows squamous metaplasia with cells weakly positive (200X), f. CK19 immunostaining in ameloblastoma, showing central cells intensely positive, with weak or negative expression in the basal and suprabasal layers (400X), g. Higher magnification of an epithelial island illustrating positiveness of CD138 mainly in the basal and suprabasal layers. Arrow shows squamous metaplasia, with peripheral cells exhibiting strong positivity, with the more central squamous cells loosening expression (400X), h. Central areas of an epithelial ameloblastic sheet showing positivity in cells presenting characteristics of squamous metaplasia (400X), i. Case of AM showing strong positiveness for β-catenin mainly in the peripheral columnar cells, loosing expression in some central cells. This strong staining was not common, as in most of the cases the labeling with β-catenin was weak or practically negative (200X).