A case of myoepithelioma in the upper lip

Abstract

A myoepithelioma is a type of salivary gland tumor composed entirely of myoepithelial cells. Previously, this was considered a subtype of pleomorphic adenoma. Here, we report an extremely rare case of myoepithelioma of the upper lip. A 33-year-old female patient presented with a painless mass on her upper lip. Magnetic resonance imaging revealed a 23 mm × 18 mm well-defined tumor. We clinically suspected a benign minor salivary gland tumor and the patient underwent complete resection of the tumor under general anesthesia. Since the tumor was diagnosed as a myoepithelioma by rapid pathological examination, it was resected with a safety margin of approximately 5 mm. Pathologically, this tumor showed mild to moderate cell atypia, and focal invasion into the capsule. Immunohistochemical findings showed that the tumor was positive for the S-100 protein and vimentin. The Ki-67 labeling index was less than 1%, and there were no malignant findings. The postoperative clinical course has been good for approximately 5 years, and satisfactory results were obtained both functionally and esthetically. Herein, we also discussed the clinical and immunohistochemical features of myoepitheliomas.