Arch Pathol Lab Med—Vol 127, April 2003 Epithelial-Myoepithelial Carcinoma of the Lung—Doganay et al e177 Case Reports Epithelial-Myoepithelial Carcinoma of the Lung A Case Report and Review of the Literature Latife Doganay, MD; Selcuk Bilgi, MD; Asli Ozdil, MD;YenerYoruk, MD; Semsi Altaner, MD; Kemal Kutlu, MD ● Primary lung tumors mimicking the salivary gland–type neoplasms are extremely rare. These types of tumors orig- inate from submucosal bronchial glands. Epithelial-myo- epithelial carcinoma is an uncommon tumor in this group, and only 7 cases have been reported. It is considered to be a low-grade malignant neoplasm. We report a case of epithelial-myoepithelial carcinoma of bronchial gland ori- gin in a 73-year-old man who presented with coughing and dyspnea. The bronchus of the left lower lobe contained a tumor mass that had a polypoid growth pattern. The tumor also extended into the pulmonary parenchyma, forming a well-circumscribed mass with a pushing margin. The tumor consisted of epithelial and myoepithelial cells. The epithe- lial cells were positive for cytokeratins and epithelial mem- brane antigen, while the myoepithelial cells were positive for S100 protein and muscle-specific actin. According to these findings, we diagnosed epithelial-myoepithelial car- cinoma. After undergoing pneumonectomy, the patient has been disease free for 34 months. (Arch Pathol Lab Med. 2003;127:e177–e180) M ucous and serous glands in the respiratory tract rare- ly produce neoplasms that are histologically iden- tical to neoplasms derived from the salivary glands of the head and neck. 1 Electron microscopic and immunohisto- chemical studies confirm the similarity between tumors in these two locations. 2 Most of these tumors are mucoepi- dermoid carcinomas, adenoid cystic carcinomas, and mixed tumors. 3 Epithelial-myoepithelial carcinoma (EMC) is a rare low-grade salivary gland neoplasm, and only 7 cases have been reported in the lung (Table). 1,2,4–8 EMC is characterized by the presence of a dual cell population that forms ductlike structures. The inner layer consists of epithelial cells, and the outer layer is formed by clear myo- epithelial cells. The clear cells may have a solid growth pattern in some areas. The epithelial cells are positive for cytokeratins, and the myoepithelial cells are positive for S100 protein, vimentin, and muscle-specific actin. 2 Because of the rarity of this tumor, we present a case and discuss the related literature. Accepted for publication October 30, 2002. From the Departments of Pathology (Drs Doganay, Bilgi, Ozdil, Al- taner, and Kutlu) and Thoracic Surgery (Dr Yoruk), Trakya University Medical Faculty, Edirne, Turkey. Corresponding author: Latife Doganay, MD, Trakya University Med- ical Faculty, Department of Pathology, 22030 Edirne, Turkey (e-mail: lcdoganay@hotmail.com, ldoganay@trakya.edu.tr). REPORT OF A CASE A 73-year-old man was admitted with coughing and dyspnea. He had smoked one pack of cigarettes daily for 30 years and had a 10-year history of diabetes. His family history was unremark- able. The results of laboratory studies were within reference lim- its. Chest radiography showed hilar condensation, and a com- puted tomography scan of the chest revealed a left hilus mass that measured 4.5 cm in diameter. Bronchoscopic examination showed a protruding mass obstructing the bronchus of the left lower lobe. A bronchoscopic biopsy was performed, and the le- sion was diagnosed as an EMC. The patient was treated with pneumonectomy. He had no further therapy. There has been no recurrence or metastasis in the 34 months since surgery. MATERIALS AND METHODS The tissue was fixed in 10% buffered formalin for 24 hours and embedded in paraffin. Sections 4 mm in thickness were prepared and stained with hematoxylin-eosin, mucicarmine, and periodic acid–Schiff without diastase predigestion. Additional sections were immunostained using the avidin-biotin complex method with peroxidase. For immunohistochemical staining, we used an- tibodies to low–molecular weight cytokeratin, high–molecular weight cytokeratin, epithelial membrane antigen (EMA), vimen- tin, muscle-specific actin, S100 protein, HMB-45, Ki-67, and p53 protein (Dako Corporation, Carpinteria, Calif). PATHOLOGIC FINDINGS Gross Features Sections of the pneumonectomy specimen contained a circumscribed, nonencapsulated mass measuring 5.0 3 4.0 3 2.5 cm. The mass was attached to the bronchus of the lower lobe and extended into the pulmonary parenchyma. The cut surface of the tumor was white and homogenous (Figure 1). There was no abnormality in the remainder of the pulmonary parenchyma. Microscopic Features The tumor was well circumscribed and nonencapsulat- ed. It extended into the pulmonary parenchyma. The bronchial epithelium was intact and covered the surface of the neoplasm in the bronchial lumen (Figure 2, a). The pulmonary component of the tumor was seen in a bron- chiolus-like space that was lined by respiratory epithelium in some areas. In the other areas, the tumor was demar- cated from pulmonary parenchyma by a thin fibrous band (Figure 2, b). The tumor cells displayed tubule formations and formed solid masses in a hyalinized stroma (Figure 2, c). The cells lining the tubules had abundant eosino- philic cytoplasm, and their nuclei were located centrally. These cells were surrounded by a second type of cells with