Pleuromediastinal Epithelial-Myoepithelial Carcinomas: A Clinicopathologic and Immunohistochemical Study of Two Cases.

OBJECTIVES: Two cases of epithelial-myoepithelial carcinoma are presented, one arising in the pleura and the other in the anterior mediastinum. The cases represent a unique distribution of these tumors within the thoracic cavity.

METHODS: Both patients were men aged 25 and 68 years, respectively, who had chest pain and dyspnea. Imaging revealed an anterior mediastinal mass in one patient and a pleural-based tumor in the other. Neither patient had any history of malignancy, and physical examination did not disclose any tumor elsewhere.

RESULTS: Initial biopsy specimens were inconclusive, and final diagnosis was deferred to surgical resection performed via median sternotomy and thoracotomy, respectively. Histologically, the lesions were characterized by epithelial and myoepithelial elements distributed as discrete tubules or duct-like structures or sheets of neoplastic cells. Immunohistochemistry showed positive staining for cytokeratin and epithelial membrane antigen in the epithelial component, while S100 protein and smooth muscle actin were expressed in the myoepithelial elements. Follow-up showed that both patients were alive 6 and 12 months after surgery, respectively.

CONCLUSIONS: These cases highlight the ubiquitous distribution of salivary gland-type tumors in the thoracic cavity. These tumors should be included in the differential diagnosis of thoracic neoplasms also in locations other than the lung.