Inverted ductal papilloma arising from the buccal minor salivary gland: A case report and immunohistochemical study

Oral inverted ductal papilloma is a rare, benign epithelial tumor that exhibits an endophytic growth pattern and is found almost exclusively in the minor salivary glands. We report on a case of inverted ductal papilloma in the buccal mucosa. We also performed an immunohistochemical study. The tumor cells were positive for cytokeratin and epithelial membrane antigen, while negative for calponin, S-100 protein, α-SMA, vimentin, and desmin. This result indicated that the lesion arises from the excretory duct near the oral mucosal surface but not the myoepithelial cells. In addition, Ki-67 labeling index of 3.96% indicated the low level of proliferation.