Pleural effusion caused by trapped lung. (Case Report).

Abstract: We report a case of pleural effusion from trapped lung secondary to sarcoidosis. The patient presented with dyspnea, right pleural effusion, left and right upper-lobe infiltrate and a widened mediastinum. The pleural effusion and dyspnea failed to respond to a course of oral corticosteroids but was relieved by decortication with stripping of inflammatory fibrous bands encasing the visceral pleural. Histologic examination of the lung, visceral and parietal pleura, and the fibrous adhesions all revealed noncaseating granulomas.

Key Words: dyspnea, pleural effusion, sarcoidosis, thoracotomy, trapped lung

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Key Points

* Trapped lung occurs when a fibroelastic peel covers the visceral pleura that prevents the lung from expanding and creates a negative pressure gradient between the lung and the chest wall.

* Trapped lung from sarcoidosis is a rare cause of pleural effusion.

* Trapped lung should be considered as a cause of pleural effusion in patients with sarcoidosis in effusions unresponsive to thoracentesis and corticosteroids.

Sarcoidosis is an idiopathic systemic granulomatous disease. It can affect any organ of the body, but most commonly affects the lungs. Pleural effusion is rare in sarcoidosis, with an incidence of approximately 2%. (1) Mechanisms of pleural effusion in sarcoidosis include direct pleural involvement, thoracic duct obstruction, and lobar atelectasis. (1,2) To our knowledge, only one previous case has ever been reported in the medical literature of pleural effusion in sarcoidosis secondary to trapped lung. (3) We present a case of pleural effusion from trapped lung secondary to sarcoidosis. Our case is unique because the effusion did not respond to corticosteroids but required thoracotomy.

Discussion

Trapped lung occurs when a fibroelastic peel is created that covers the visceral pleura on part or all of a lung lobe. It does not allow the lobe to expand to the chest wall. Negative pressure between the chest wall and the nonexpanding lung is created and fluid migrates into the pleural space in response to the negative pressure. This is an end-stage complication of various inflammatory processes. Simple thoracentesis is not successful as the negative pressure gradient remains and the effusion re-accumulates. Pleurodesis is seldom successful because complete apposition of pleural surfaces cannot be achieved before pleurodesis. Causes of trapped lung include empyema, malignancy, postcardiac and pericardial surgery, rheumatoid arthritis, uremic pericarditis, hemothorax, tuberculosis, and histoplasmosis. (4) To our knowledge, there has been only one previous reported patient with a trapped lung from sarcoidosis, (3) and that patient's pleural effusion resolved with corticosteroids. Specific causes of trapped l ung that may be prevented include early evacuation of persistent pleural effusion after cardiac surgery (5) and complete evacuation of hemothorax in trauma patients. (6) The standard treatment is decortication of the inflammatory fibrous bands. The placement of small-bore indwelling drainage catheters in patients with advanced malignant pleural effusion with trapped lung can alleviate dyspnea. (7)

Our patient required decortication of her trapped right lung. Although the patient's right lower and middle lung lobes did not completely reexpand, the patient noted marked improvement in her dyspnea. We suspect that decortication was not able to remove all the fibrosis responsible for lung entrapment. Trapped lung should be considered as a cause of pleural effusion in sarcoidosis patients with extensive pulmonary parenchymal disease and pleural effusions that fail to respond to corticosteroids and thoracentesis.

Accepted January 15, 2002.

References

(1.) Soskel NT, Sharma OP. Pleural involvement in sarcoidosis: Case presentation and detailed review of the literature. Semin Respir Med 1992;13: 492-5 14.

(2.) Poe RH. Middle-lobe atelectasis due to sareoidosis with pleural effusion. N Y State J Med 1978;78:2095-2097.

(3.) Claiborne RA, Kerby GR. Pleural sarcoidosis with massive effusion and lung entrapment. Kans Med 1990;91(4):103-105.

(4.) Cohen M, Sahn SA. Resolution of pleural effusions. C/zest 2001;119:1547-1562.

(5.) Kollef MH. Trapped-lung syndrome after cardiac surgery: A potentially preventable complication of pleural injury. Heart Lung 1990;19:671-675.

(6.) Lee YC, Vaz MA, Ely KA, McDonald EC, Thompson PJ, Nesbitt JC, et al. Symptomatic persistent post-coronary artery bypass graft pleural effusions requiring operative treatment: Clinical and histologic features. Chest 2001;119:795-800.

(7.) Pien GW, Gant MJ, Washam CL, Sterman DH. Use of an implantable pleural catheter for trapped lung syndrome in patients with malignant pleural effusion. Chest 2001;119:1641-1646.

RELATED ARTICLE: Case Report

A 65-year-old woman with a remote history of tobacco use presented with cough, shortness of breath, and wheezing for one month. Physical examination revealed decreased breath sounds over the right chest. Initial chest x-ray revealed a right upper lobe infiltrate, right pleural effusion, a small left upper lobe infiltrate, and a widened mediastinum (Fig. 1). Transbronchial lung biopsy revealed noncaseating granulomas. Acid-fast bacilli and fungal stains of the biopsy were negative. A thoracentesis revealed serosanguinous fluid with a red blood cell count of 218/ [mm.sup.3]; a white blood cell count of 2,420/[mm.sup.3], 69%, lymphocytes, 31% neutrophils; total protein 4.3 g/dl; glucose 104 mg/dl; amylase 36 IU/L; cholesterol 82 mg/dl; triglycerides 29 mg/dl. Gram's stain, acid-fast bacilli, fungal stains, and cytology of the pleural fluid were negative. A chest computed tomographic scan revealed a loculated right pleural effusion and right lung consolidation (Fig. 2).

The patient had transient relief of dyspnea after the thoracentesis; however, pleural fluid reaccumulated within one month. A therapeutic thoracentesis was therefore repeated. The patient was started on 10 mg prednisone daily and increased to 30 mg/d over 4 months without relief of her dyspnea or pleural effusion. Methotrexate 12.5 mg/wk was subsequently added without symptomatic or radiographic improvement. The persistence of the pleural effusion and lack of response to steroids and methotrexate raised concern that a process other than sarcoidosis was responsible. Thoracoscopy was therefore performed for definitive diagnosis and possible pleurodesis. Thoracoscopy revealed dense fibrous bands throughout the right lung. This fibrosis prevented the middle and lower lobes from expanding completely and limited expansion of the right upper lobe. The parietal pleura was stripped and decortication was attempted; however, the lung did not completely reexpand because of extensive residual fibrous adhesions. Multiple b iopsies of right lung and parietal pleura all showed noncaseating granulomas. After the surgical procedure, the pleural effusion resolved. The patient had a residual small loculated right pneumothorax and her right middle and lower lung lobes remained consolidated. Clinically, the patient noted marked improvement in her dyspnea.

From the Department of Medicine and the Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, Charleston, Sc.

Reprint requests to Marc A. Judson, MD, Division of Pulmonary and Critical Care Medicine, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425.

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