Epithelial-myoepithelial carcinoma of the maxillary sinus: a rare case.

Epithelial-myoepithelial carcinoma (EMC) is a rare tumor that commonly involves the salivary glands. EMC of the maxillary sinus is extremely rare. We describe here a case of a 50-year-old patient who presented with right cheek swelling for 7 years and bilateral nasal obstruction and right nasal bleeding for 3 months. A pinkish polypoidal mass was seen in the right nasal cavity. Computed tomography scan revealed an expansile soft tissue mass in the right maxillary sinus with erosion of all of its walls. Histopathological examination of the excised specimen confirmed myoepithelial carcinoma with positive reaction to S-100 and smooth muscle actin. Subsequently, the patient developed regional nodal metastasis in the neck for which neck dissection was performed. Histopathology of the neck dissection specimen revealed metastatic EMC. EMC is rare tumor and a diagnostic dilemma. It should be considered in cases showing dual tumor cell population with clear cell change in histopathology. Common differential diagnosis includes metastatic renal cell carcinoma, acinic cell carcinoma, adenoid cystic carcinoma, mucoepidermoid carcinoma, oncocytoma, and sebaceous carcinoma. Laryngoscope, 2012.