Ann Thorac Surg 2002;73:1952-1954
© 2002 The Society of Thoracic Surgeons
Case report
Giant mediastinal chordoma
A.M. Rahman, MDa,
Iman G. Farahat, MSa,
Wael A. Ali, MSa,
Kamal A. Mansour, MDb*
a Departments of Surgery and Pathology, National Cancer Institute, Cairo University, Cairo, Egypt
b Department of Cardiothoracic Surgery, Emory University School of Medicine, Atlanta, Georgia USA
Accepted for publication December 5, 2001.
* Address reprint requests to Dr Mansour, Department of Cardiothoracic Surgery, 1365 Clifton Rd, NE, Atlanta, GA 30322 USA
e-mail: kamal_mansour{at}emoryhealthcare.org
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Abstract
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A chordoma is a slow-growing tumor representing about 5% of all malignant bone tumors. Mediastinal chordoma is very rare. We report a giant thoracic chordoma in a 32-year-old woman who presented with chest pain, progressive dyspnea, and cough. Open biopsy confirmed a definitive preoperative diagnosis, and complete surgical excision of the tumor was accomplished.
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Introduction
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Chordomas are rare malignant neoplasms presumed to be derived from remnants of the embryonic notochord [1]. While these tumors show a sharp predilection for the axial skeleton, particularly the base of the skull and sacrococcygeal region, a minority of cases may arise from the cervical, thoracic, and lumbar spine. An age-adjusted chordoma incidence of 0.08 per 100,000 was age dependent, more common in males, and rare among blacks and patients aged less than 40 years [2]. Thoracic chordomas occur mostly in the upper thoracic spine at the level of the third and fourth vertebrae [3]. Only 9 patients who had total resections were reported in the English literature.
A 32-year-old Egyptian woman was admitted to the hospital complaining of persistent chest pain radiating to the back, progressive dyspnea, and irritating cough. Clinical examination revealed diminished breath sounds and localized tenderness over the posterior part of the ribs and upper thoracic spine. Plain chest roentgenogram revealed a well-defined large posterior superior mediastinal mass with no bony destruction. Computed tomographic scan of the chest showed a large, well-defined mass (12 x 10 x 9 cm) in the upper posterior mediastinum, mainly on the right side, anterior to the upper thoracic vertebrae with no plane of cleavage between them. The mass was heterogeneous with areas of calcification pushing the trachea and esophagus anteriorly and crossing the midline to the left side (Fig 1).
Magnetic resonance imaging of the chest revealed a heterogeneous tumor shadow at T2 weighted image with anterior displacement of the great vessels and aorta. Caudally, the tumor extended to the level of the cardiac atria. Fiberoptic bronchoscopy showed broad carina with displacement anteriorly and to the left associated with mucosal congestion and edema. Radio isotopic bone scan revealed no distant bony metastases. Repeated computed tomography guided biopsies failed to reach a definite diagnosis and preoperative diagnosis was possible only after open biopsy through a limited right thoracotomy. On June 21, 2001, exploration through a fifth right posterolateral thoracotomy was performed. The right lung and pleura were completely free. There was a firm well-defined mediastinal mass with hard bony-like areas, extending from the second to sixth ribs. It crossed in front of the vertebral column to the left, pushing the carina and the esophagus anteriorly. The mass was separate from the superior vena cava and the esophagus and the azygos major vein stretched across it. Extrapleural dissection was reached by opening the mediastinal pleura and ligating the azygos vein. With careful sharp and blunt dissection, the mass was chiseled out with apparent complete removal. There was no invasion of the vertebral column that would necessitate removal of vertebral bodies. The patient had a smooth postoperative course and was discharged on postoperative day 10. She was referred for postoperative radiotherapy.
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Fig 1. Computed tomographic scan showing heterogeneous mass with areas of calcification significantly displacing the trachea and esophagus anteriorly.
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Grossly, the mass measured 12 x 9 x 6.5 cm and weighed about 500 gm. The cut section was nodular and composed of grayish yellow soft tissue with areas of hemorrhage mixed with bone. The anterior surface was covered by pleura, whereas the posterior surface was raw. Microscopically, the tumor showed the classic feature of chordoma, which is a prominent lobular growth pattern on scanning magnification. On higher magnification, the tumor was composed of sheets of large cells with abundant vacuolated cytoplasm and large hyperchromatic nuclei, mixed with small round and stellate cells with scanty cytoplasm and hyperchromatic nuclei. The tumor cells were embedded in an abundant myxoid stroma. Scattered throughout were large cells featuring bubbly vacuolated cytoplasm characteristic of physaliphorous cells (Fig 2).
Areas of necrosis and hemorrhage were identified within the tumor as well as foci of extravasation of hemosiderin pigment and accumulation of foamy macrophages. The tumor cells stained strongly positive with broad-spectrum cytokeratins (Fig 2), vimentin, and S-100 protein, and with lesser intensity with epithelial membrane antigen (EMA). Stains for desmins were negative.
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Fig 2. Area of tumor showing large cells with abundant, bubbly vacuolated cytoplasm typical of physaliphorous cells (H and E magnification x400). [Inset] Large vacuolated cells showing immunoreactivity with broad-spectrum cytokeratins (magnification x200).
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Comment
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Chordoma is a malignant bone tumor that grows slowly, often recurs locally and metastasizes late. It exhibits notochordal differentiation. In human embryonal development, it forms as an axial structure that attains its complete maturation in 10 to 11 mm embryo. Subsequently, it undergoes gradual involution and fragmentation by the ossification centers of the axial skeleton [4]. During the second month of embryonal development, the notochord is restricted to the intervertebral residues. In adults, it forms the nucleus pulposus of the intervertebral discs. The remnants of the notochord tissue are referred to as ecchordosis physaliphora [5].
Chordoma is a relatively rare tumor, accounting for 3% to 5% of primary malignant bone tumors in major series. With nearly 90% of cases occurring in the sacrococcygeal region and in the base of the skull, involvement of the thoracic spine is extremely rare [5]. The tumor is characterized by slow but relentless local progression; it metastasizes late, but it has an aggressive tendency to recur at the surgical site, which makes it highly lethal. Clinically, the patient may be asymptomatic but usually presents with symptoms related to compression or involvement of the adjacent structures, including the trachea, esophagus, and spinal cord [6]. Radiographically, vertebral body destruction may be present. The lesions are usually lytic, but scattered discrete opacities representing intralesional calcification may be present. Computed tomography and magnetic resonance imaging are indispensable in evaluating the extent of both the lesion and the involvement of the adjacent structures. On T2-weighted magnetic resonance images, septae of low signal intensity radiate throughout the large high-signal mass; this feature may be of use in differentiating chordoma from other posterior mediastinal masses [7]. Vacuolization of the cytoplasm is almost invariably present, frequently in the form of large (single or several) vacuoles displacing the nucleus peripherally and causing so-called signet ring-like appearance. Occasionally the vacuoles encircle the nucleus, which remain centered in the cytoplasm and produce the so-called physaliphorous appearance. Mitoses are rare. By immunohistochemistry, the tumor cells stain strongly positive with anti-cytokeratin (CAM 5.2) and low molecular weight keratin, and with lesser intensity with broad-spectrum keratin, EMA, vimentin, and S-100 protein.
In our patient, the histologic examination of the tumor showed the characteristic features of chordoma. The tumor was easily distinguishable from metastatic mucinous carcinoma of the signet-ring cell type by the characteristic lobulated, low power appearance of the tumor and the presence of the distinctive multi-vacuolated physaliphorous cells. The tumor was differentiated from chondrosarcoma by the positive reaction with cytokeratins and EMA in the tumor cells. Surgical resection is the only curative procedure for chordomas. A wide margin is crucial to local control because these lesions are generally unresponsive to radiotherapy and chemotherapy. Whereas only 5% of patients with spinal chordomas have metastases develop, nearly 70% will die of their disease, reflecting the seriousness of local tumor extension.
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References
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Abstract
Introduction
