Myoepithelioma Arising in the Buccal Mucosa: A Case Report and Review of the Literature.

Although myoepithelioma is defined as a benign tumour made up primarily of neoplastic myoepithelial cells, its actual histopathological characteristics are highly diverse. It can be considered a rare disease. The most common site of occurrence is the parotid gland, followed by the minor salivary glands of the palate. Very little has been reported about its occurrence in the buccal mucosa. We present a case of a 55-year-old woman with myoepithelioma arising in the buccal mucosa who was referred to our hospital for swelling of the buccal mucosa. Contrast-enhanced computed tomography revealed a mass measuring approximately 18 mm in diameter in the left lateral buccal mucosa, and the interior of the mass showed slight heterogeneous enhancement. Magnetic resonance imaging revealed an almost low signal intensity comparable to that of the muscle on T1-weighted imaging and an irregular mixture of low and high signal intensities on T2-weighted imaging. The tumour was diagnosed as a pleomorphic adenoma based on biopsy results and resected under general anaesthesia. The final diagnosis was myoepithelioma, which requires careful differentiation from pleomorphic adenoma. At 32 months after surgery, no evidence of recurrence was detected.