Asian Cardiovasc Thorac Ann 2007;15:e46-e48
© 2007 Asia Publishing EXchange Ltd
Left Atrial Malignant Mesenchymoma — Emergency Resection and Mitral Replacement
Ganesh Shanmugam, FRCS,
Ian Colquhoun, FRCS
Department of Cardio-Thoracic Surgery, Glasgow Royal Infirmary, Glasgow, United Kingdom
For reprint information contact: Ganesh Shanmugam, FRCS Tel: 44 141 211 4503 Fax: 44 141 201 9204 Email: sgunpat{at}hotmail.com, Department of Cardio-Thoracic Surgery, Glasgow Royal Infirmary, 84 Castle Street, Glasgow G4 0SF, Scotland, United Kingdom.
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ABSTRACT
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Cardiac mesenchymoma is a rare malignancy with a dismal prognosis. We present a case of left atrial mesenchymoma, obstructing the mitral orifice. An emergent tumor resection with mitral valve replacement was performed. Few reports deal with emergency resection of cardiac malignancies with mitral valve replacement. Surgery is the only effective treatment modality.
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CASE REPORT
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A 56-year-old lady was admitted with cardiac failure, pulmonary edema, and atrial fibrillation. She had a recent history of fever with leukocytosis. A chest X-Ray showed cardiomegaly, pulmonary edema, and bilateral pleural effusions. Transthoracic echocardiography revealed a large left atrial (LA) mass. On transesophageal echocardiography (Figure 1
) the mass was seen to obstruct transmitral flow and extend to the pulmonary veins. The patient experienced rapid hemodynamic deterioration and an emergency resection was required.
Standard cardiopulmonary bypass (CPB) was established through a sternotomy and cardioplegic arrest achieved by using antegrade cold blood cardioplegia. The entire LA was filled with a tumor mass, which arose from a poorly demarcated base but did not extensively infiltrate or adhere to the atrial wall. It obstructed the mitral orifice, and extended to the pulmonary veins. A plane of dissection was established and the tumor was completely resected leaving an intact LA. The pulmonary venous components were completely excised. The involved mitral leaflets were excised and replaced with a 29-ATS bi-leaflet prosthesis (ATS Medical, Minneapolis, MN, USA). The patient was weaned from bypass without incident.
Frozen section indicated undifferentiated sarcoma. Histopathology showed pleomorphic spindle shaped cells, with areas of hyalinization and hemorrhagic necrosis. Well-demarcated areas of chondrosarcomatous, leiomyosarcomatous, and liposarcomatous differentiation and foci of osteogenic sarcoma were identified. There were also areas of high-grade undifferentiated sarcoma. The mass was characterized as a malignant mesenchyoma. Immunohistochemical staining showed positivity for vimentin, desmin, smooth muscle actin, and focal staining for S100. The postoperative course was uneventful. The patient was discharged home a week later. Adjuvant chemotherapy was not administered. The patient remains asymptomatic at follow-up. Echocardiography showed normal ventricular and prosthesis function, with no evidence of intracardiac tumor or metastases.
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DISCUSSION
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Malignant mesenchymomas are composed of multiple cell types that derive from primitive mesenchyme. The tumor arises from congenitally misplaced mesenchymal cells or from a primitive precursor mesenchymal cell with incomplete, immature or deviated differentiation. Cardiac malignancies present by one of the following mechanisms: obstruction to blood flow and interference with valve function; arrhythmias or pericardial effusion; embolic phenomena from tumor fragments or peri-tumoral thrombus; symptoms of cardiac failure or systemic symptoms. Our patient presented with fever, malaise, and dyspnea which suggested a myxoma. The differential diagnosis includes cardiac sarcomas, infective endocarditis, and infected myxoma.
Cardiac sarcomas are often confused with myxomas. Myxomas have a narrow pedicle attached to the atrial septum. Features suggestive of sarcoma include a broad base of attachment, an aggressive growth pattern, combined intramural and intracavity location, pulmonary vein involvement, infiltrative growth, and a non-septal location. Three-dimensional echocardiography and magnetic resonance imaging (MRI) have been advocated for the morphologic and spatial characterization of cardiac tumors. Magnetic resonance imaging is also useful in assessing tumor response to surgery, radiation, and chemotherapy.
The large tumor size makes assessment of the precise site of origin impossible. Tumors can originate primarily from the mitral valve, the left atrium, pulmonary veins or the lung and secondarily involve the other structures. This determines the surgical approach and extent of resection. With predominant pulmonary parenchymal, minimal pulmonary venous, and LA involvement, an appropriate lung resection through a thoracotomy is appropriate. With right thoractomies, it is possible to establish bypass, and achieve a LA, if required. For left-sided tumors, left thoracotomy is preferred, as the left hilum is not easily accessed through a sternotomy without elevation of the beating heart. If a sternotomy is used, dissection and reconstruction may require the use of bypass. Greater pulmonary venous, LA, atrial septal, and mitral involvement warrant a more radical resection, through a sternotomy using CPB. Surgery involves en bloc resection of the tumor, the PV, LA free wall, and the septum (if involved). When the pulmonary vein orifices are involved, the tumor can be shelled out, if it is intraluminal and free floating. Tumors densely adherent to the pulmonary venous wall warrant resection of the pulmonary veins, and an appropriate pulmonary resection. If the pulmonary resection cannot be accomplished through the sternotomy, a separate lateral thoracotomy is required. Following resection, the residual defect can be reconstructed with a patch of autologous or bovine pericardium, the free wall of the right atrium or the left atrial appendage.
Mitral valve involvement mandates complete resection and mitral valve replacement (MVR). Huang et al1 reported 2 cases of primary mitral tumors. In one patient, the tumor was considered benign and only tumor resection was performed. The patient died of local recurrence shortly thereafter. In our patient, the tumor involved the mitral valve, but was not adherent to the LA wall or pulmonary veins. Although our patient is currently disease free, the possibility of subsequent local recurrence or metastases exists. Given that there was a well-defined plane of dissection and an absence of extensive infiltration of the LA in our patient, a resection of the LA/pulmonary veins would be difficult to justify, in the absence of definite evidence that such a resection would confer a survival advantage. There is inadequate data to suggest the preferential use of a mechanical or a biological valve in such cases. The risks of anticoagulation and limited survival should be balanced against the potential for complete tumor clearance and the possibility of recurrence. In young patients with complete tumor clearance, where longer survival is anticipated, a mechanical valve may be preferred. In elderly patients, those with limited survival, and those with contraindications to anticoagulation, a biological valve may be preferred. The choice of valve is determined by the usual factors for valve selection as well as the characteristics of the cardiac tumor. Multiple resections have been described for local recurrence, but the outlook is poor. Putnam and colleagues2 reported cases of repeat resection with survival less than 30 months.
To achieve complete resection, Reardon et al3 used a technique of cardiac explantation, extracorporeal resection of the tumor with cardiac reconstruction, and autotransplantation. Although their patient died of metastatic disease, there was no evidence of local recurrence at autopsy. In patients with unresectable cardiac tumors and who are free of metastases, total cardiectomy with transplantation is an alternative. The risk of tumor recurrence or metastasis and the possible enhancement of tumor growth by immunosuppression are issues of concern. Transplantation is limited by donor organ availability, which makes it a less viable option particularly in an emergent situation.
Given the likely inadequacy of surgical margins and the risk of metastases, adjuvant therapy has been recommended. However, in the absence of randomized trials, it is unknown whether adjuvant therapy is beneficial. Complete surgical resection is the only factor that has influenced survival.4 In the French experience, postoperative doxorubicin based chemotherapy failed to modify prognosis.4
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CONCLUSION
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Factors determining survival5 are left sided lesions, absence of necroses and metastases, and low mitotic count. Emergency resection of cardiac malignancies with MVR is exceedingly rare. In our patient emergent resection was mandatory, as the tumor had virtually obliterated the mitral orifice causing hemodynamic instability. Radical resections, "bench surgery," and transplantation reduce local recurrence, but the risk of metastasis remains. The role of adjuvant therapy is controversial. Prognosis is poor in symptomatic patients but early diagnosis and aggressive treatment may improve survival.
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REFERENCES
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- Huang Z, Sun L, Du M, Ruan Y, Wang H. Primary cardiac valve tumors: early and late results of surgical treatment in 10 patients. Ann Thorac Surg 2003;76:1609–13.[Abstract/Free Full Text]
- Putnam JB Jr, Sweeney MS, Colon R, Lanza LA, Frazier OH, Cooley DA. Primary cardiac sarcomas. Ann Thorac Surg 1991;51:906–10.[Abstract]
- Reardon MJ, DeFelice CA, Sheinbaum R, Baldwin JC. Cardiac autotransplant for surgical treatment of a malignant neoplasm. Ann Thorac Surg 1999;67:1793–5.[Abstract/Free Full Text]
- Llombart-Cussac A, Pivot X, Contesso G, Rhor-Alvarado A, Delord JP, Spielmann M, et al. Adjuvant chemotherapy for primary cardiac sarcomas: the IGR experience. Br J Cancer 1998;78:1624–8.[Medline]
- Burke AP, Cowan D, Virmani R. Primary sarcomas of the heart. Cancer 1992;69:387–95.[Medline]
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