A Case of Mucoepidermoid Carcinoma with Clear Cell Components Occurring in Retromolar Region

Mucoepidermoid carcinomas in the minor salivary glands usually originate in the palatine gland, and their occurrence in the retromolar region is rare. We report a rare case of mucoepidermoid carcinoma with clear cell components occurring in the retromolar region. The patient was a 63-year-old woman referred to our hospital with the chief complaint of a painless mass in the right retromolar region initially found during treatment at a local dental clinic. The 20×10-mm mass was well-defined, elastic, and flexible. The surface of the mucosa was healthy. The mass was clinically diagnosed as a gingival benign tumor in the right retromolar region. There were no significant findings in the patient's medical history. The tumor was resected under local anesthesia. Histopathology revealed that squamoid cells, undifferentiated intermediate cells, and clear cells were dominant, with mucus-producing cells in some areas. A mucoepidermoid carcinoma with clear cell components was diagnosed. There were no signs of recurrence or metastasis at 15 months postoperatively and the patient's progress has been satisfactory. Because the tumor was a painless, slow-growing mass, it was clinically diagnosed as a benign tumor of the gingiva, and resection was performed under local anesthesia without performing a biopsy. However, even if a mass in the retromolar region is clinically diagnosed as a benign tumor, the course of treatment should be decided after performing fine-needle aspiration cytology, taking into consideration the possibility of mucoepidermoid carcinoma.