Myoepithelial carcinoma commonly arises in the parotid and palatal glands and consists of spindleshaped, plasmacytoid, epithelioid, and glycogen-rich clear cells. Myoepithelial carcinoma is fairly rare and only accounts for approximately 0.4% of all salivary gland tumors. This report describes a case of myoepithelial carcinoma arising from myoepithelioma in the palate. However, the diagnosis made from a biopsy specimen was myoepithelioma, because the tissue taken from the tumor surface was composed of myoepithelial cells without atypia. The patient was an 83-year-old woman with a chief complaint of a painless swelling in the right side of the palate since November 2009. She was referred to our hospital for comprehensive examination and treatment by her physician in February 2010. Initial examination revealed an elevated mass approximately 17×15 mm in diameter with ulceration of the palatal mucosa. No enlargement of the corresponding lymph nodes was present. The mass was palpable without tenderness. Enhanced computed tomography showed a radiopaque lesion 15 mm in diameter, with no evidence of bone invasion. However, the lesion extended to the medial plate of the pterygoid process. A biopsy specimen showed the characteristics of myoepithelioma, without atypical tumor cells. The tumor cells were densely branched, but nuclear atypia and mitotic figures were not apparent. The lesion was resected, and the surgical defect was covered by a buccal fat pad with the patient under general anesthesia in March 2010. Histopathological examination revealed areas of myoepithelial carcinoma showing cellular atypia and high proliferative activity intermingled with myoepithelioma. A final diagnosis of myoepithelial carcinoma arising from myoepithelioma was established. The patient's postoperative course was uneventful with no functional disturbance, recurrence, or metastasis during 3 years of follow-up.
