Imaging in Oncology (ANSWER)

Answer:

2. postoperative changes related to a pleural tent procedure

Discussion

    The chest radiograph shows changes related to a pleural tent procedure. The pleural tent procedure was first described in 1956 and was performed to reduce the apical pleural dead space and to prevent overdistension of the remaining lung following lung resection for pulmonary tuberculosis.¹ It has recently been adapted to reduce air leaks following upper lobe surgery in carcinoma and bullous emphysema. Robinson and Preksto² have recently described a reduced chest tube time and reduced total hospitalization time in patients with carcinoma whose upper lobectomies were supplemented by pleural tenting. The procedure entails extrapleural mobilization of the parietal pleura in the apex of the chest cavity, allowing it to drape down over the visceral pleura of the remaining lung. This eliminates intrapleural dead space and allows the parietal pleura to seal staple lines in the visceral pleural surface of the remaining lung. Thus, the air leaks seal rapidly, and chest tube time and overall hospitalization time are significantly decreased.

    Venugopal et al³ have described the postoperative radiographic evolution following pleural tenting in patients undergoing upper lobectomy for carcinoma of the lung. A characteristic progression was identified in 80% of patients. On postoperative day 1, there is generally an area of lucency in the apical region that could be mistaken for a pneumothorax. This lucency is caused by extrapleural air. On day 2, fluid is commonly seen to enter the extrapleural space producing an air fluid level. By day 3, the prominent fluid in the extrapleural space could be mistaken for a hydropneumothorax. Over the following month, the air fluid level disappears as the remaining lung expands and the air and extrapleural fluid is resorbed, leaving a fibrinous rind around the apex of the expanded lung. Computed tomography images obtained at this time demonstrate apical soft-tissue density that could be mistaken for an apical lung mass (Fig 2A). The images at the level of the aortic arch and great vessels demonstrate a beak-shaped nodular density along the chest wall that could be mistaken for a pleural-based nodule (Fig 2B). A computed tomography scan of the chest taken one year postoperatively shows a decrease in the size of both these densities as the amount of fluid in the extrapleural space decreases and the lung undergoes progressive expansion.

    Reviewing sequential postoperative chest radiographs enables the radiologist to identify complications of the pleural tenting procedure. Any increase in the size of the extrapleural space could indicate the development of an infection or hemothorax, or it may indicate the development of pneumothorax, which is usually in a subpulmonic location.

    The use of the pleural tenting procedure is increasing since it reduces morbidity, length of hospital stay, and costs. Radiologists, surgeons, and oncologists should be familiar with the radiographic appearance of the chest following this procedure in order to avoid the misdiagnosis of pneumothorax/hydropneumothorax on plain chest radiographs and the misdiagnosis of apical lung mass or pleural-based nodules on computed tomography scans of the thorax.

References

1. Miscall L, Duffy RW, Nolan RB. The pleural tent as a simultaneous tailoring procedure in combination with pulmonary resection. Am Rev Tuberc. 1956;73:831-852.

2. Robinson LA, Preksto D. Pleural tenting during upper lobectomy decreases chest tube time and total hospitalization days. J Thoracic and Cardiovasc Surg. 1998. In press.

3. Venugopal PR, Berman CG, Robinson LA. The pleural tent: radiologic appearance of the chest. Am J Roentgenol. Submitted.

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