Fig. 10

Histopathological findings of the excised specimen. A, B A large amount of dentinoid tissue and proliferation of tumor cells in the fibrous connective tissue was observed. The tumor showed solid growth, with tumor cells having a cystic morphology. (Hematoxylin Eosin staining, A scale bar 1000 μm, B scale bar 500 μm). C A cluster of ghost cells (arrowheads) were observed in the tumor nests containing stellate reticulum-like cells. (Hematoxylin Eosin staining, scale bar 100 μm, *: dentinoid tissue). D The cuboidal or columnar epithelial cells, similar to ameloblasts, presented at the periphery of the tumor nests and lined dentinoid tissues. Almost no nuclear division of tumor cells was observed. (Hematoxylin Eosin staining scale bar 100 μm, *: dentinoid tissue). E The cytoplasm and membrane were positive for cytokeratin AE1/AE3 (immunohistochemical staining scale bar 50 μm). F The nucleus and cytoplasm were positive for β-catenin (immunohistochemical staining scale bar 50 μm). G MIB1 (Ki67) index was < 3% (immunohistochemical staining scale bar 50 μm)