Intra-pericardial recurrent thymoma presenting with compression of the pulmonary trunk

Abstract

A patient who had a second recurrent intra-pericardial thymoma is presented. The tumor was expanding in the pericardial space and compressed the pulmonary trunk. The obstruction of the pulmonary trunk could have resulted in a fatal outcome. Surgical management was required, and complete surgical resection and mediastinal adjuvant radiation therapy were effective in this patient’s management.

Introduction

Recurrence of thymoma is more likely to be intra-thoracic, followed by local relapse and systemic metastasis. Most intra-thoracic metastases are pleurally disseminated, and surgical therapy is commonly considered in localized cases. On the other hand, surgical cases of intra-pericardial recurrence are rare. A patient who had second intra-pericardial recurrence after complete resection of B3 invasive thymoma with myasthenia gravis (MG) is described. The tumor was expanding in the pericardial space and compressed the pulmonary trunk. Surgical management and postoperative radiation therapy improved the patient’s outcome.

Case report

A 38-year-old woman presented with a second intra-pericardial thymoma recurrence, discovered during systemic follow-up. Five years earlier, she had a complete en bloc resection of B3 thymoma (Masaoka stage III) complicated with MG. In this case, early-stage thymoma measuring 3 cm in the right anterior mediastinum was discovered. Video-assisted thoracic surgery (VATS) extended thymectomy was planned by the bilateral approach in the lateral decubitus position. The left lateral side approach was done first. During the subsequent right lateral side approach, the tumor was seen to extend locally into the right middle lobe and pericardium, without extension into any large vessels. Conversion to lateral thoracotomy was done, and radical extended thymectomy was performed with partial resection of the lung and pericardium and reconstruction of the pericardium. She was given adjuvant radiation therapy (46 Gy) following complete resection. The first recurrence occurred 3 years and 4 months later as a solitary pulmonary metastasis measuring 1 cm in the right lower lobe, which was removed by VATS. Twenty months later, a chest X-ray showed enlargement of the left lung hilum. Enhanced chest computed tomography (CT) showed a soft tissue tumor, 54 mm × 30 mm in size, adjacent to the pulmonary trunk on the left side of the pericardial space. The pulmonary trunk was compressed and narrowed by the tumor (Figure 1). Positron tomography scans showed increased isotope uptake of this lesion, suggesting localized intra-pericardial recurrence of thymoma. At that time, she had no symptoms related to the tumor. By median sternotomy, the pericardium was opened (Figure 2(a)). The tumor was not invading the pulmonary artery and could be removed along the adventitia of the pulmonary trunk (Figure 2(b)). The pericardial involvement was resected with small margin and the tumor was macroscopically removed completely. There was no residual tumor visible elsewhere. The pericardial defect was covered with a polytetrafluoroethylene sheet. On pathological examination, the resected tumor was found to be a B2 (and not a B3) thymoma. Pathologic findings were similar to those at initial diagnosis. The patient was then treated with adjuvant radiation therapy (50.4 Gy). She has had no signs of recurrence for 2 years and 10 months after the third surgery.

Figure 1.

Enhanced chest computed tomography scan showing the pulmonary trunk compressed by the intra-pericardial tumor.

Figure 2.

Intraoperative view. (a) Exposed tumor after pericardiotomy with yellow tape (passed through the phrenic nerve). (b) Removing the tumor along the adventitia of the pulmonary vessels, and the pulmonary trunk appears. AO: aorta; PT: pulmonary trunk; *: tumor.

Discussion

According to several studies, the recurrence rates following complete resection of stage III thymoma varied from 28% to 35%.^1,2 Recurrence was more common in pleural lesions, followed by local relapse.^1,3,4 Distant metastasis and intra-pericardial recurrences were rare, with Masaoka stage 3 and B2, B3 thymoma being predictors of recurrence.^4,5 This patient was therefore thought to have a greater risk of pleural or local recurrence. She was followed up every 3 months with alternating chest X-rays and thoracic CT scans. In addition, there were several unexpected events occurring in her past history. The initial tumor was only 3 cm, and did not have CT findings associated with thymoma invasiveness, such as a lobulated tumor contour, and infiltration of surrounding fat, but it had already infiltrated adjacent organs. There was no major vessel involvement, which is often associated with distant metastasis. ⁵ However, pulmonary metastasis and subsequent intra-pericardial recurrence developed 40 and 60 months, respectively, after the initial complete resection.

The surgical strategy for recurrent thymoma is controversial, especially for pleural recurrence. ¹ Complete resection might offer long-term survival.^4,6,7 The second intra-pericardial recurrent tumor had expanded into the pericardial space and compressed the pulmonary trunk. Although she was asymptomatic, obstruction of the pulmonary trunk could have resulted in a fatal outcome. Surgical resection was considered, even if it would have resulted in subtotal resection. The tumor was not invasive and could be macroscopically removed completely. Intra-thoracic examination was done using a thoracoscope, with no other recurrent lesions found. The second intra-pericardial recurrence presumably occurred as a consequence of tumor-cell spillage from the mediastinum during handling of the pericardium outside of the radiation therapy field. This study might be interpreted as suggesting that VATS techniques might expose the patient to intra-thoracic relapse, but this case does not imply that. The VATS procedure was completed before the pericardium was opened. Pericardiotomy and its reconstruction were done following conversion to lateral thoracotomy. If tumor seeding occurred during VATS procedures, tumor implantation might also have occurred in the pleural cavity. Seven years has passed since the initial surgery, with no pleural recurrences. The sternotomy provides a much better exposure and control of the procedure. However, in late 1990s, mini-thoracotomy (with a 6 cm incision) was applied to cardiac surgery, and it evolved into new and safe method of access. ⁸ Since exfoliation of right-side mediastinal tissues was already completed, surgery could be done without additional mediastinostomy.

Complete surgical resections of recurrent tumor and mediastinal adjuvant radiation therapy were effective in this patient’s management. Her MG has been well managed without episodes of MG crisis since the initial surgery. She has so far survived for 94 months after initial surgery and for 36 months after the third surgery without tumor recurrence.