Multiple canalicular adenomas arising in the buccal mucosa and upper lip: Case report and literature review

Canalicular adenomas are uncommon benign salivary gland tumors that typically arise from minor salivary glands. They are usually solitary tumors; only a few cases of multiple tumors have been reported. We describe an unusual case of canalicular adenomas that appeared simultaneously in the buccal mucosa and upper lip of an elderly Japanese woman. Microscopic examination revealed that the tumors were composed of columnar cells in a canal-like structure and accompanied by cystic cavities. Immunohistochemical evaluation further revealed that the tumor cells were positive for CK7, CK14, and S100, whereas staining yielded negative results for β-catenin, calponin, Ki-67 protein, p63, and α-smooth muscle actin (α-SMA). We also review previous reports of cases of multiple canalicular adenomas and discuss their clinical features.