Ann Thorac Surg 2004;77:334-336
© 2004 The Society of Thoracic Surgeons
Case report
Surgical management of leiomyosarcoma of the mediastinum
William C. Conner, MD*a,
Gregory W. Fink, MDa,
Karen M. McGinnis, MDa,
George M. Alfieris, MDa
a Department of Surgery, State University of New York, Upstate Medical Center, Syracuse, New York, USA
Accepted for publication April 29, 2003.
* Address reprint requests to Dr Shiraishi, Division of Pediatrics, Children's Research Hospital, Kyoto Prefectural University of Medicine, Kyoto, Japan 602-8566.
e-mail: isao{at}koto.kpu-m.ac.jp
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Abstract
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Leiomyosarcoma of the mediastinum is sufficiently rare; therefore therapeutic approaches are not well defined. Current therapy primarily rests with the thoracic surgeon. We report a single case of a large leiomyosarcoma of the mediastinum invading the heart and right lung. Our diagnostic and therapeutic approach to this patient is presented and the pertinent literature is reviewed. We conclude that little advancement has been made with regard to adjuvant therapies for leiomyosarcoma of the mediastinum, and the only opportunity for cure remains with full surgical extirpation.
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Introduction
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Leiomyosarcoma of the mediastinum generally arises from nests of mesenchymal cells within the loose areolar tissue of the mediastinum, referred to as the visceral mediastinum. It can also arise from the great vessels. It is important to make this distinction, because tumors arising from the visceral mediastinum are less common [1]. We present a case of leiomyosarcoma arising from the visceral mediastinum.
A 41-year-old woman was treated for pneumonia after she presented with symptoms and right lower lobe infiltrate on chest x-ray. Despite a good clinical response to antibiotic therapy she continued to have a persistent infiltrate. A large mediastinal mass involving the right pulmonary hilum and left atrium was found after a computed tomographic scan was performed for this persistent roentgenogram abnormality (Fig 1).
Transesophageal echocardiography demonstrated the mass invading the left atrium and obstructing the right superior pulmonary vein. Next we performed flexible bronchoscopy with biopsy, esophagoscopy with endoscopic ultrasound guided biopsy, and computed tomographic guided percutaneous needle biopsy. Flexible bronchoscopy revealed extrinsic obstruction of the right lower lobe bronchus, but transbronchial biopsy was nondiagnostic. Esophagoscopy with endoscopic ultrasound excluded esophageal involvement, but demonstrated a tumor in the right posterior mediastinum replacing the pulmonary hilum and invading the heart. Unfortunately transesophageal needle biopsy was nondiagnostic. Likewise, computed tomographic guided percutaneous needle biopsy failed to yield a diagnosis.
Because of the failure of the previously described methods, a surgical biopsy was done by thoracoscopy. Histologic evaluation demonstrated a spindle cell neoplasm. A more specific diagnosis was not possible based on the limited tissue available. In the absence of gross metastatic disease, we recommended surgical removal of the tumor for cure, which would require right pneumonectomy and partial left atrial resection.
After median sternotomy we identified the tumor arising from the right posterior mediastinum, invading up into the right pulmonary hilum and left heart. The tumor was lateral and separated from the more anteriorly located main right pulmonary artery. The patient was placed on cardiopulmonary bypass. After cardiac arrest was achieved, the right pulmonary artery and right main stem bronchus were divided. The right atrium was opened and the interatrial septum divided. The tumor was identified in the posterior superior left atrium with complete obstruction of the right superior pulmonary vein. The right atrium was separated from the left atrium allowing for en bloc removal of the tumor in continuity with the orifice of the right superior and inferior pulmonary veins, the right pericardium, and the right lung. The left atrium and right atrium primarily were reconstructed. The patient was weaned from cardiopulmonary bypass after establishing an electromechanical rhythm. A Gore-Tex patch (W.L. Gore & Assoc, Flagstaff, AZ) was used to reconstruct the right-sided pericardium to prevent cardiac herniation. The patient was hospitalized for 2 weeks postoperatively. She required a second operation for a suspected postoperative empyema. This necessitated removal of the prosthetic patch, evacuation of a right chest hematoma, and instillation of antibiotics into the evacuated pleural cavity. The patient was asymptomatic for a 9-month period when she returned with a recurrent empyema treated with tube thoracostomy and intrapleural antibiotics. She is now 19 months from her initial operation with no signs of recurrent tumor or infection.
On gross examination the tumor originated from the mediastinum, posterior and outside the heart. The tumor was also inferior to and separate from the right pulmonary artery (Fig 2).
Routine hematoxylin and eosin staining revealed abundant cellularity and undifferentiated spindle cells with variable mitotic activity. There was no microscopic evidence that the tumor arose from a blood vessel. Immunohistochemical stains were strongly positive for both smooth muscle actin and desmins, but negative for caldesmon and S-100 protein. Electron microscopy demonstrated prominent intracellular longitudinal bundles of filaments with focal densities and desmosome-like junctions. Taken together, the gross examination, the cytomorphology, immunophenotype, and electron microscopy best characterized a high-grade leiomyosarcoma. Furthermore, because the pulmonary artery was clearly distinct from the tumor, both on gross and microscopic examinations, we concluded that the most likely origin was from within the visceral mediastinum.
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Fig 2. Pathologic specimen demonstrating the tumor and its relationship to the right lung, pulmonary hilum, and left atrium.
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Comment
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Leiomyosarcoma of the visceral mediastinum is a rare tumor. The literature contains a few sporadic individual case reports [2–4]. However, in 1994, Moran and colleagues [5] described a series of 10 patients with primary leiomyosarcoma of the visceral mediastinum. This report provides the most comprehensive information regarding demographics, presentation, diagnosis, and treatment ever published. The mean age of the patients was 56 years (range, 26 to 71 years). There were 7 men and 3 women, and most of these patients were asymptomatic. The diagnosis of a mass was suspected by a widened mediastinum on chest roentgenogram, but the definitive anatomic study was chest computed tomography. Surgical biopsy for tissue diagnosis was often required because of the scant tissue obtained with less invasive techniques. The only treatment was surgical extirpation. Recurrences usually occurred within 2 to 3 years, with most patients having a recurrence of the disease causing death. Five-year survival was 15% to 20%, which was limited to those patients with complete surgical excision. No patient received adjuvant radiotherapy or chemotherapy.
It is difficult to draw any sound conclusions based on individual case reports and a single retrospective cohort of patients. However, survival does seem dependent on adequacy of surgical resection. The lack of support for adjuvant therapy after surgery most likely reflects the rare incidence of this tumor and the inexperience in treatment. Therefore the thoracic surgeon must know that the only opportunity for a cure relies on a very aggressive surgical approach. If cure is the goal of therapy, then it is recommended that an aggressive attempt at removal should be made with any patient, even if it requires cardiopulmonary bypass.
In conclusion, leiomyosarcoma of the visceral mediastinum remains a very rare tumor, usually found by accident in asymptomatic patients by computed tomography of the chest. Though technically challenging, the mainstay of treatment remains en bloc surgical excision. Therefore, aggressive surgical action is required when dealing with this tumor if any hope of survival is to be realized.
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References
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- Shields T.W., Robinson P.G. Mesenchymal tumors of the mediastinum. In: Shields T.W., LoCicero J., III, Ponn R.B., eds. General thoracic surgery. Philadelphia: Lippincott Williams & Wilkins, 2000:2371-2372.
- Rasaretnam R., Panabokke R.G. Leiomyosarcoma of the mediastinum. Br J Dis Chest 1975;69:63-69.[Medline]
- Sunderrajan E.V., Luger A.M., Rosenholtz M.J., Maltby J.D. Leiomyosarcoma in the mediastinum presenting as superior vena cava syndrome. Cancer 1984;53:2553-2556.[Medline]
- Steen B.C., Florez M.S., Fernandez F.L., Garcia T.J., Jareno E.J., Ancochea B.J. Mediastinal leiomyosarcoma. An Med Interna 1993;10:83-85.[Medline]
- Moran C.A., Suster S., Perino G., Kaneko M., Koss M.N. Malignant smooth muscle tumors presenting as mediastinal soft tissue masses: a clinicopathologic study of 10 cases. Cancer 1994;74:2251-2260.[Medline]
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Abstract
Introduction
