IS Case 567: Trapped lung secondary to papillary adenocarcinoma
Imaging Sciences URMC 2010
Publication Date: 2011-11-16
Patient is a 47-year-old woman, nonsmoker, presenting with history of 3 months of cough and 1 month of dyspnea on exertion.
Trapped lung secondary to papillary adenocarcinoma
The incidence of trapped lung is unknown. Trapped lung can result from malignant and nonmalignant disease and may also be a sequela of a remote inflammatory condition which has resolved, but left behind a collagenous or fibrous peel. The visceral pleura becomes encased with a fibrous peel or rind and a trapped lung occurs. The lung is prevented from expanding and this creates a negative pressure gradient causing a chronic fluid-filled pleural space.
The diagnosis of trapped lung is not always obvious because many patients with trapped lung do not have symptoms. However, the diagnosis should be suspected in any patient with a stable chronic pleural effusion and if on the radiographs the hemithorax with effusion is reduced in size because it indicates that the pleural pressure on the side with the effusion is more negative than that on the contralateral side. Unfortunately, similar findings can be seen with endobronchial obstruction and therefore should be included in the differential diagnosis. Another differential diagnosis to keep in mind is pneumothorax. In contrast to pneumothorax, the trapped lung radiographically does not appear larger on expiration than on inspiration and the visceral pleural line delineates the scarred lung contour. The diagnosis of trapped lung are confirmed when the underlying lung does not expand radiographically after thoracentesis or tube thoracostomy.
The treatment of the trapped lung depends on the patient's symptoms. In symptomatic patients with underlying normal lung parenchyma the definitive therapy of trapped lung is pleurectomy and decortication. Extended drainage by pleural catheter may be a reasonable alternative, particularly in patients in whom more invasive procedures may pose too great a risk. The apposition of the visceral and parietal pleura can not be achieved; therefore sclerosis attempts are not successful. Likewise, there is no role for serial thoracentesis since the pleural effusion recurs rapidly after each thoracentesis.
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