A Case of Myoepithelial Carcinoma of the Parotid Gland

Abstract

Myoepithelial carcinoma of the salivary gland is a rarely occurring tumor. We report a case of myoepithelial carcinoma of the parotid gland. A 66-year-old male visited our hospital with a left parotid mass. CT revealed a mass measuring 5.0×4.0 cm in size in the left parotid gland. Aspiration biopsy of the mass was indeterminate. Partial resection of the left parotid gland was performed under the diagnosis of suspected parotid gland carcinoma (cT4aN0M0). Then, surgery to remove the enlarged regional swollen lymph nodes was performed at the same time. Histopathological examination of the surgical specimen showed proliferating atypical spindle-shaped cells. Immunohistochemical study revealed positive staining of the carcinoma cells for cytokeratin, vimentin, and S-100 protein, and slightly positive staining for p53, p63 and MIB-1 (Ki-67). Histopathologically, the resected tumor was diagnosed as myoepithelial carcinoma (pT4aN2b). Since we judged it as a high-grade carcinoma, post-operative radiation therapy was administered at 60 Gy. Eight months later, the patient was found to have multiple metastases in the lung. The lung metastases did not show any response to PF (cisplatin, 5FU) therapy. We therefore started treatment with TS-1 (120 mg/body) to maintain a good QOL of the patient. He developed adverse events 8 months later, therefore, the treatment was switched to UFT (300 mg/body). Finally, the patient died 2 years and 9 months after the operation without local recurrence.