Epithelial-myoepithelial carcinomas of the bronchus

Epithelial-myoepithelial carcinomas are very rare in the lung, and little i s known about the relationship of their histologic features to prognosis. W e describe five primary pulmonary epithelial-myoepithelial carcinomas with details on clinical presentation, histology, and immunohistochemical profil es. We also reviewed the literature to detail further their prognosis. The patients' ages ranged from 33 to 57 years (average 51 years), The tumors we re all endobronchial and the patients presented with symptoms or imaging fe atures of airway obstruction. The tumors were completely resected none show ed nodal involvement. All five patients are alive and free of disease 4 mon ths to 8 years (average 4.2 years) after surgery. Four tumors showed a mixe d pattern of glands lined by a dual layer of cells and solid sheets of eith er spindle cells or clear cells, the glandular and solid components being p resent in variable proportions. The fifth tumor comprised purely spindle ce lls. The mitotic rate was <1/20 high power fields in both the glandular and spindle/clear cell components. In one case there was focal nuclear pleomor phism. The inner layer of the glands stained for cytokeratins and epithelia l membrane antigen, and the outer layer for S-100 and smooth muscle actin. In one case the spindle cells stained for CD34. A review of published cases shows the majority of tumors behave in an indolent fashion, the rare aggre ssive tumors being predominantly myoepitheliomatous. Nevertheless, the term epithelial-myoepithelial carcinoma is preferred because of their malignant potential. A high mitotic rate, tumoral necrosis. and nuclear pleomorphism appear to be adverse prognostic factors.