Epithelial-myoepithelial carcinoma arising in the nasal cavity: a case report and review of literature.

Epithelial-myoepithelial carcinoma is an uncommon, low-grade, malignant epithelial neoplasm composed of variable proportions of ductular cells and large, clear staining, myoepithelial cells arranged around the periphery of the ducts. About 120 cases have been reported in the world literature, most of which were located in salivary glands, except for a few cases occurring in unusual locations such as breast, lacrimal gland, nose, paranasal sinus, trachea, bronchus, and lung. We here reported the second case of epithelial-myoepithelial carcinoma of the nasal cavity with extension to the nasopharynx. The patient was a 61 year old Chinese female with two month's history of progressive nasal obstruction. Histopathologically, the tumor showed typical myoepithelial and ductal cells biphasic differentiation, duct-like structure and infiltrating growth pattern. Some ductal cells showed the characteristics of oxyphilic cell, which had never been reported before. Recurrence and metastasis rates of epithelial-myoepithelial carcinoma varied from 35% to 50% and 8.1% to 25% respectively in different reports. The present case had neither recurrence nor metastasis twenty months after operation. When epithelial-myoepithelial carcinoma is mainly composed of spindle myoepithelial cells, the differential diagnosis should include myoepithelioma, neurofibroma, leiomyoma and hemangiopericytoma.