What is fibrothorax?

What is Fibrothorax?

Fibrothorax is a restrictive pleural condition characterized by dense fibrotic thickening of the visceral and/or parietal pleura that encases the lung, restricting its expansion and causing respiratory impairment. 1, 2

Pathophysiology and Development

Fibrothorax develops when inflammatory processes in the pleural space trigger an abnormal healing response, leading to excessive collagen deposition and pleural symphysis. 2 The condition represents a failure of normal pleural healing mechanisms, where the pleural mesothelial cell loses its integrity and disordered fibrin turnover occurs. 2

• The fibrotic process can involve both the visceral pleura (covering the lung) and parietal pleura (lining the chest wall), with calcification occurring on both surfaces contrary to older beliefs. 3
• The thickened pleural "peel" physically restricts lung expansion, creating a restrictive ventilatory defect that impairs gas exchange. 1, 2

Common Etiologies

The clinical spectrum of fibrothorax can be differentiated into pleural fibrosis versus lung parenchymal fibrosis, which have distinct causes and presentations. 1

Pleural-based causes include:

• Complicated parapneumonic effusions and empyema (most common cause). 2
• Hemothorax with inadequate drainage. 2
• Rheumatoid pleural effusion, which can evolve into a sterile empyematous exudate leading to fibrothorax and lung restriction. 4
• Tuberculous pleuritis. 1, 2
• Asbestos exposure (asbestosis). 5
• Uremic pleuritis in end-stage renal failure patients. 5

Parenchymal-based causes include:

• Drug-induced lung disease. 5
• Chronic hypersensitivity pneumonitis. 5
• Connective tissue diseases. 5

Clinical Presentation

• Patients typically present with progressive dyspnea on exertion and reduced exercise tolerance due to restrictive lung mechanics. 1, 2
• Physical examination reveals decreased chest wall expansion on the affected side, dullness to percussion, and diminished breath sounds. 1
• The condition is more common in middle-aged men, particularly when associated with rheumatoid arthritis. 4

Diagnostic Approach

Imaging findings:

• Chest radiography shows pleural thickening, often with calcification creating a "rind" around the lung. 3
• CT scanning demonstrates dense pleural thickening with underlying lung compression and volume loss. 1
• Calcification can appear on both visceral and parietal pleural surfaces. 3

Pulmonary function testing:

• Restrictive pattern with reduced total lung capacity and vital capacity. 1, 2
• Preserved or increased FEV1/FVC ratio distinguishes this from obstructive disease. 2

Complications and Long-Term Sequelae

• Chronic calcified fibrothorax may harbor a fluid-filled cavity that can become infected after prolonged latency, sometimes decades later. 3
• Reactivation or superinfection can occur, often associated with bronchopleural or pleurocutaneous fistula formation. 3
• In rheumatoid pleural effusion cases, superimposed infective empyema frequently complicates the fibrothorax. 4
• Progressive respiratory failure occurs in severe cases with extensive pleural encasement. 1, 2

Management Strategies

Prevention is paramount and differs by etiology:

• For pleural-based disease: Adequate and timely drainage of pleural collections (empyema, hemothorax) is the physician's responsibility to prevent fibrothorax development. 1
• For parenchymal disease: Patient medication compliance is critical to prevent primary lung parenchymal fibrosis. 1

Treatment options for established fibrothorax:

• Decortication surgery (removal of the fibrotic pleural peel) improves lung function and clinical outcomes in selected patients. 5, 4
• Lung release procedures can benefit patients with significant functional impairment. 5
• For rheumatoid-associated fibrothorax: Oral, parenteral, or intrapleural corticosteroids, pleurodesis, and decortication have all been utilized, though optimal therapy remains undefined. 4
• Infected empyema complicating fibrothorax requires drainage and antibiotics. 4

Key Clinical Pitfalls

• Do not delay drainage of complicated pleural effusions, as inadequate or delayed drainage is the primary preventable cause of pleural fibrothorax. 1, 2
• In patients with rheumatoid arthritis presenting with pleural effusion but no arthritis symptoms, pleural biopsy is mandatory to exclude tuberculosis or malignancy before attributing the effusion to rheumatoid disease. 4
• Chronic calcified fibrothorax can reactivate after very long latent periods (years to decades), so maintain vigilance for signs of infection even in longstanding stable disease. 3
• Surgical decortication should be considered early in symptomatic patients, as the procedure becomes more difficult and less effective as the fibrotic process matures and calcifies. 5, 2