Epithelial-myoepithelial carcinoma of a minor salivary gland in the buccal mucosa

Epithelial-myoepithelial carcinoma (EMC) is a rare tumor constituting less than 1 % of all salivary gland tumors. This neoplasm most often involves the parotid glands, with less frequent involvement of the submandibular or minor salivary glands. This case report describes EMC arising from a minor salivary gland in the buccal mucosa. A 71-year-old Japanese man with a painless submucosal mass in the left buccal region was referred to our hospital. The patient stated that the tumor had been present for more than 4 years and was painless but increasing in size. Oral examination showed a mobile, well-defined mass of approximately 19 x 15 mm; its surface was covered mostly by normal mucosa. Magnetic resonance imaging showed a mass with well-defined borders and relative homogeneity internally. Incisional biopsy led to a histological diagnosis of a suspected pleomorphic adenoma or low-grade malignant tumor originating from the salivary gland. The patient underwent surgical excision under general anesthesia to obtain a definitive diagnosis, and EMC was diagnosed based on histopathological and immunohistochemical examination of the whole specimen. Because the surgical margins were positive in some areas, the patient underwent external postoperative radiotherapy (total of 60 Gy at 2 Gy/day). Recovery was uneventful, and good function returned after postoperative treatment. Four years after tumor resection and radiotherapy, no recurrence had been detected and no other lesions had developed.