We report a case of mediastinal malignant peripheral nerve sheath tumor (MPNST) in a patient with neurofibromatosis type 1 (NF-1, von Recklinghausen disease). The tumor had a complex involvement with mediastinal structures and was resected by a temporary aortic transection approach under cardiopulmonary bypass (CPB).
Clinical summary
A 40-year-old man with NF-1 was referred to our hospital because of hoarseness and enlargement of an abnormal shadow on his chest radiograph. On admission to our hospital, chest computed tomographic (CT) scan showed multiple masses in the mediastinum and chest wall. The largest one, measuring 12 × 9 × 8 cm, was centered in the aortopulmonary window, encasing the ascending aorta and compressing the right pulmonary artery, left atrium, and left main bronchus (Figure 1). Compared with his chest CT 4 years previously, this mediastinal lesion showed marked growth, whereas the other masses had remained unchanged in size. A CT-guided needle biopsy revealed MPNST immunohistochemically positive for S-100 protein. We initially chose systemic chemotherapy with cisplatin and doxorubicin to reduce tumor size, but chemotherapy proved ineffective. We then planned as a lifesaving measure to surgically resect the tumor to relieve its compression of vital structures. To best gain access to this complex lesion, we elected to temporarily transect the ascending aorta under CPB.
A median sternotomy and a left anteroaxillary thoracotomy through the fourth intercostal space were performed. An elastic, firm tumor was found densely attached to the ascending aorta, right pulmonary artery, and trachea. We exfoliated the tumor adhesion meticulously but could not proceed around the central right pulmonary artery because of tumor invasion into the vessel wall. At this time we observed the patient's blood pressure, heart rate, and arterial blood oxygenation dropping drastically in response to tumor manipulation. CPB was therefore started with femoral artery and inferior caval cannulation. After induction of cardiac arrest, the ascending aorta was doubly clamped and transected. Excellent tumor exposure was now achieved through these cut ends of the aorta (Figure 2). On closer examination, it was suspected that the tumor also had invaded the descending aorta. A combined vessel wall resection was thus necessary at these sites, but only the pulmonary artery was resected. If a complete resection of the tumor had been the aim, selective cerebral perfusion and replacement of the descending aorta would also have been required. Because we did not wish to take on such a surgical challenge, we were able to remove only a portion of the tumor. The pulmonary artery defect was reconstructed with a polytetrafluoroethylene tube graft. The unresectable part of the tumor remained in place around the descending aorta. The ends of the transected ascending aorta were anastomosed, and CPB was terminated without difficulty. The patient's postoperative course was uneventful, and he received postoperative radiotherapy to the mediastinum totaling 70 Gy. Twelve months after the operation, the patient is doing well with no mediastinal recurrence.
Figure 2. Intraoperative view after transecting ascending aorta. Ad, Cut end of ascending aorta (distal side); PA, right pulmonary artery; Ap, cut end of ascending aorta (proximal side); T, tumor.
Discussion
MPNST is a rare kind of tumor, usually associated with NF-1, that typically arises from a simple or plexiform neurofibroma. The tumor in this case was considered to have arisen from a neurofibroma of the left vagus and recurrent laryngeal nerve. In patients with NF-1, malignant transformation of neurofibromas, which occurs in 2% to 16% of cases, is considered to be a poor prognostic factor.1, 2 Because MPNST is associated with frequent local recurrence and metastasis, especially in patients with NF-1, surgical intervention has been the best form of treatment for these tumors. In this case the tumor was large, had a complex involvement with mediastinal structures, and was in a life-threatening location. Because the patient was relatively young, in good general condition, and free of other cardiopulmonary disorders, we chose an aggressive surgical approach.
Surgical techniques requiring CPB for advanced thoracic malignancies have been discussed and are considered beneficial in appropriate patients.3 Temporarily dividing great vessels, such as the ascending aorta, to remove a tumor constitutes the last resort. To our knowledge this approach has not been previously reported. Under CPB, resection of this tumor by mobilizing the ascending aorta might have been possible, even without aortic transection, but this approach would have encountered enormous technical difficulties. We decided that a temporary aortic transection approach would provide better surgical exposure and enable manipulation of the tumor, which we hoped would shorten the cardiac arrest time. Although our procedure resulted in incomplete excision, we achieved our primary purpose of preventing cardiopulmonary collapse as a result of tumor compression. This case demonstrates that a temporary aortic transection approach may be justified for appropriate patients who otherwise would have no viable treatment option.
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Vaporciyan AA, Rice D, Correa AM, Walsh G, Putnam JB, Swisher S, et al.Resection of advanced thoracic malignancies requiring cardiopulmonary bypass. Eur J Cardiothorac Surg. 2002;22:47–52. Abstract | Full Text |
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aFirst Department of Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
Address for reprints: Katsuyuki Asai, MD, Department of Thoracic Surgery, Numazu City Hospital, 550 Harunoki Higashi-shiiji, Numazu, Shizuoka 410-0302, Japan
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