Ann Thorac Surg 2007;83:689-691
© 2007 The Society of Thoracic Surgeons
Case Reports
Bronchial Epithelial-Myoepithelial Carcinoma
Tung-Ying Chao, MDa,*,
An-Shen Lin, MD,
Chien-Hao Lie, MDa,
Yu-Hsiu Chung, MDc,
Jui-Wei Lin, MDb,
Meng-Chih Lin, MDc
a Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Chiayi, Taiwan
b Department of Pathology, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine, Kaohsiung, Chiayi, Taiwan
c Department of Respiratory Care, Chang Gung Institute of Technology, Chiayi, Taiwan
Accepted for publication July 13, 2006.
* Address correspondence to Dr Chao, Pulmonary and Critical Care Division, Chang Gung Memorial Hospital-Kaohsiung Medical Center, Chang Gung University College of Medicine; No 123, Ta-Pei Rd, Niao-Sung Hsiang, Kaohsiung County, Taiwan. (Email: tychao{at}adm.cgmh.org.tw).
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Abstract
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An epithelial-myoepithelial tumor is an extremely rare pulmonary neoplasm. Only 21 cases have been reported to date. This report presents a case of left main bronchial epithelial-myoepithelial carcinoma in a 43-year-old woman. No mediastinal lymph nodes were enlarged in computed tomographic scan, and no tumor growth was noted beyond the bronchial cartilage layer by endobronchial ultrasound imaging. This report highlights the usefulness of endobronchial ultrasound imaging for determining the depth of tumor invasion and choosing an alternative approach to surgical resection.
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Introduction
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Although epithelial-myoepithelial tumors are relatively common in salivary glands, they are rarely found in the respiratory tract [1]. To date, 21 cases with various biologic features have been reported in the lung [2, 3]. This report describes an epithelial-myoepithelial carcinoma obstructing the left main bronchus in a 43-year-old woman. Endobronchial ultrasound (EBUS) imaging demonstrated that tumor growth was limited to the bronchial cartilage layer. We used EBUS imaging to assist in the staging of this tumor and treated it with electrocautery.
A 43-year-old woman (nonsmoker) presented with progressive exertional dyspnea after right thyroid goiter surgery at a local hospital 1 year earlier. The patient denied having weight loss, bloody sputum, and any cough. The physical examination showed expiratory wheezing over the left chest. The chest roentgenogram finding was normal. Spirometry indicated a forced expiratory volume of first second of 1.24 liters, forced vital capacity 1.70 liters, and the percentage of forced expiratory volume in 1 second was 57.4%.
A computed tomographic (CT) chest scan revealed a 2-cm endobronchial tumor mass over the distal left main bronchus without mediastinal lymph node enlargement. Bronchoscopy revealed a 2-cm well-circumscribed hypervascular tumor located at the anterolateral wall of the left main bronchus, 2.5 cm distal to the carina (Fig 1A). The movable tumor obstructed nearly 90% of the lumen, but the scope could pass through the narrowed route without causing bleeding from the tumor.
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Fig 1. (A) Bronchoscopic picture shows a 2-cm well-circumscribed, hypervascular tumor that nearly totally obstructs the left main bronchus. (B) No residual tumor was identified over left distal main bronchus 3 months after electrocauterization.
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A forceps biopsy was used to obtain a specimen for histologic diagnosis, and electrocauterization was used to control bleeding and for temporary relief of dyspnea. Microscopically, the tumor showed ductular and a solid architecture. The solid section consisted of plasmacytoid cells. The glands were composed of an inner layer of epithelial cells and an outer layer of myoepithelial cells (Figs 2 and 3).
No cell atypia or mitosis was noted. Ductal epithelial cells were positive for cytokeratin 7 and epithelial membrane antigen. Myoepithelial cells were positive for smooth muscle actin and S100. No cytokeratin 20, neuron-specific enolase, chromogranin A, or synaptophysin was found in the tumor cells. Most of the tumor cells were also positive for P53 and CD117. About 2.8% of the tumor cells stained positive for Ki-67, indicating low-grade malignancy.
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Fig 2. Neoplastic plump cells with focal ductular formation (hematoxylin and eosin stain, original magnification x100).
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Fig 3. Florid neoplastic cells in sheets with plasmacytoid appearance (hematoxylin and eosin stain, original magnification x200).
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Surgical resection was advised, but the patient refused because of the possibility of pneumectomy. EBUS imaging later showed that tumor growth was limited to the bronchial cartilage layer; therefore, curative electrosurgery was performed. Three months later, a chest CT scan and a bronchoscopic examination demonstrated no residual lesions over the distal left main bronchus (Fig 1B). The specimen from a repeated bronchoscopic biopsy at 3 and 6 months revealed only chronic inflammation.
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Comment
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Epithelial-myoepithelial carcinomas arising in the lung are very rare. Only 21 cases have been reported [2, 3]. Diagnosis is based on the identification of myoepithelial cells, with spindle cells, clear cells, or plasmacytoid differentiation or a mixture of phenotypes, along with a variable abundance of duct-forming epithelium. Immunohistochemically, the basal layer of the glandular elements is shown to be myoepithelium by staining for S-100 and smooth muscle actin. The luminal layer stained positive for cytokeratin and epithelial membrane antigen. Tumors described as predominantly myoepitheliomatous are aggressive and have a high mitotic rate. The presence of tumor necrosis and nuclear pleomorphism are typically adverse prognostic factors. Immunochemical staining with the lower Ki-67 index generally means low-grade malignancy [2, 3].
In all reported cases, the tumor site was predominantly endobronchial, with one exception. Clinical symptoms presented as endobronchial lesions with dyspnea and cough. All patients underwent complete resection (lobectomy or pneumonectomy) [2]. Distant metastases are extremely rare [4, 5].
Clinically, this patient had no obstructive pneumonitis or distant metastases by chest CT scan and low-grade malignancy on the pathologic view. Surgical resection was still advised to ensure tumor eradication; however, because of the possibility of pneumectomy, this young healthy patient rejected surgical treatment. Curative electrocauterization was done under the assurance of limited bronchial airway invasion by EBUS imaging.
EBUS has been available for several years and is an exceptional instrument in differentiating between endobronchial tumors that have infiltrated the airway and those that are just compressing it [6, 7]. In this case, EBUS imaging did not show tumor growth beyond the cartilage layer.
Electrocauterization is useful for controlling bleeding, debulking, and removal of endobronchial tumors [8]. The outcome has been acceptable thus far, and regular, long-term follow-up of the patient is mandatory. Curative electrosurgery is an option for management of this rare low-grade malignancy. In our opinion, EBUS imaging is useful for preoperative diagnosis and treatment of an endobronchial tumor.
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References
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Abstract
Introduction
