Giant myoepithelioma of the upper lip

Myoepithelioma is a relatively rare form of salivary gland tumor composed entirely of myoepithelial cells. This tumor was formerly considered to be a subtype of pleomorphic adenoma; however, in the latest World Health Organization classification of 1991 it is listed as an independent entity. We report herein an extremely rare case of myoepithelioma of the upper lip. A 78-year-old Japanese female presented with a huge, painless mass on her upper lip. CT and MRI revealed a 50 x 40 mm(2) well-defined ovoid tumor. A benign minor salivary gland tumor was clinically suspected, and the patient underwent complete resection of the tumor under general anesthesia. The surgical defect was immediately reconstructed using an Abbe-Estlander flap. The tumor was histopathologically diagnosed as a benign myoepithelioma of the minor salivary gland. Immunohistochemically, the tumor cells were positive for vimentin, cytokeratins, alpha-smooth muscle actin and S-100 protein, confirming the morphological diagnosis of myoepithelioma. The patient's postoperative clinical course was uneventful, and satisfactory results were obtained both functionally and esthetically. The pathology, clinical manifestations and treatment of myoepithelioma are reviewed.