Epithelial-myoepthelial carcinoma of the tracheobronchial tree: the prognostic role of myoepithelial cells

Objectives Epithelial myoepithelial carcinoma (EMC) of the lung is a very rare tumor that is characterized by biphasic differentiation of epithelial and myoepithelial cells. Current discussion about this entity focuses on the malignant potential of the tumor and the role of myoepithelial cells in diagnosis and patient prognosis. This study reports five EMC cases in the lung and discusses issues related to EMC prognosis. Materials and methods The five EMC cases were diagnosed and collected at the Samsung Medical Center (Seoul, Korea) from 1998 to 2012. Four patients with EMC were received a lobectomy and one patient was given a bronchoscopy to excise the tumor. All cases were evaluated with hematoxylin and eosin and immunohistochemical staining, which included S-100 protein, smooth muscle actin, TTF-1, cytokeratin, vimentin, and p27 analysis. Results and conclusion All cases revealed biphasic differentiation of epithelial and myoepithelial tumor cells with various stromal patterns. One of the cases contained predominantly myoepithelial and focal epithelial differentiation, and the tumor showed recurrence and metastasized to the chest wall. This was the first case of metastatic pulmonary EMC. Therefore, we suggest that EMC of the lung has a malignant potential, and that myoepithelial tumor cells may be associated with a pulmonary EMC prognosis.