Epithelial-Myoepithelial Carcinoma of the Salivary Glands: Clinical Aspects and Treatment Outcome

Kim, Kwang Hyun; Sung, Myung Whun; Lee, Chang Ho; Rhee, Chae Seo; Yun, Ja Bock; Mo, Ji Hun; Min, Yang Gi

Abstract

BACKGROUND: The epithelial-myoepithelial carcinoma(EMC) of major and minor salivary glands is a low grade malignancy which shows frequent local recurrence.
OBJECTIVES
The aim of this study was to define the clinical feature and treatment outcome of EMC of major and minor salivary glands.
MATERIALS AND METHODS
Nine cases of EMC of major and minor salivary glands were reviewed retrospectively.
RESULTS
The clinical course varied from slowly growing painless mass to the mass associated with facial nerve paralysis, bleeding or bone desutruction. Local recurrence was observed in 3 cases(33%) at 3, 10 and 11 months after primary resection, but no metastasis to periglandular, cervical lymph nodes or distant site occurred in our series including three recurrences. One of three recurrent patients died due to local extension of the tumor. Other two patients with recurrent tumors were successfully treated with revision operation and survived more than 2, 6 years without disease, respectively so far. Preoperatively these tumors were usually regarded as benign salivary gland tumor in CT scan except for the cases showing bone destruction. Atypical cells on fine needle aspiration cytology/frozen biopsy coupled with benign looking CT finding suggested low grade malignancy in which case EMC should be considered a differential diagnosis. Pathologic diagnosis was frequently confused with other high grade carcinoma rather than low grade carcinoma or benign tumor. This resulted in unnecessary postoperative radiotherapy, but clinically aggressive recurrent cases recurred despite radiotherapy. No malignant cells were found in clinically enlarged lymph nodes, and we have to retain positve attitude toward surgical management of advanced or recurrent EMC keeping in mind that recurrent tumor may inherit different tumor bilogy.
CONCLUSION
Although epithelial-myoepithelial carcinoma is a rare salivary gland tumor, otolaryngologists should be aware of its existence because this low grade malignancy can cause diagnostic confusion during workup and also frequently be misdiagnosed as other high grade salivary malignancy in clinically aggressive form.