| Fibrothorax | |
|---|---|
 | |
| Fibrothorax on chest x-ray | |
| Specialty | Respiratory medicine |
| Symptoms | Breathlessness |
| Usual onset | Adulthood |
| Duration | Long-term |
| Causes | Haemothorax,empyema,tuberculosis,collagen vascular diseases,uraemia,rheumatoid arthritis,pleurodesis,pleural effusion, certain medications |
| Risk factors | Asbestos exposure, certain drugs |
| Diagnostic method | Chest X-ray, CT scan |
| Treatment | Watchful waiting,decortication |
| Prognosis | Variable |
| Frequency | Rare |
Fibrothorax is a medical condition characterised by severe scarring (fibrosis) and fusion of the layers of thepleural space surrounding thelungs resulting in decreased movement of the lung and ribcage.[1] The main symptom of fibrothorax isshortness of breath. There also may be recurrentfluid collections surrounding the lungs. Fibrothorax may occur as a complication of many diseases, including infection of the pleural space known as anempyema or bleeding into the pleural space known as ahaemothorax.[2]
Fibrosis in the pleura may be produced intentionally using a technique calledpleurodesis to prevent recurrent punctured lung (pneumothorax), and the usually limited fibrosis that this produces can rarely be extensive enough to lead to fibrothorax.[3] The condition is most often diagnosed using anX-ray orCT scan, the latter more readily detecting mild cases. Fibrothorax is often treated conservatively withwatchful waiting but may require surgery. The outlook is usually good as long as there is no underlyingpulmonary fibrosis or complications following surgery. The disease is highly uncommon.
Reduced movement of the ribcage during breathing, reduced breath sounds on the affected side(s), and a dull feeling when the chest is pressed are common signs observed during examination for fibrothorax.[4]Sharp chest pain with deep breaths or coughing may be seen in some cases.[3] Severe cases of fibrothorax can lead torespiratory failure due to inadequateventilation and causeabnormally high levels of carbon dioxide in the bloodstream.[3]
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The condition only causes symptoms if the visceral pleura is affected.[5] Although fibrothorax may not cause any symptoms, people affected by the disorder may reportshortness of breath.[6] Persistent, recurrentpleural effusions are a possible symptom, caused by the persistent cavity formed by the hardening pleura around the original fluid collection.[4] Shortness of breath tends to develop gradually and may worsen over time. Less commonly, fibrothorax may cause chest discomfort or a drycough.[4] Fibrothorax may occur as a complication of other diseases. Symptoms of the underlying problem are sometimes seen, for example, fever in cases ofempyema.
Fibrothorax is often a complication of other diseases that causeinflammation of the pleura. These include infections such as an empyema ortuberculosis, or bleeding within the pleural space known as ahaemothorax. Exposure to certain substances, such asasbestos, can cause generalised fibrosis of the lungs, which may involve the pleura and lead to fibrothorax.[7] Less common causes of fibrothorax includecollagen vascular diseases such assystemic lupus erythematosus,sarcoidosis, andrheumatoid arthritis;kidney failure leading touraemia; and side effects of certain medications.[3][8] The medications most commonly associated with pleural fibrosis are theergotalkaloidsbromocriptine,pergolide, andmethysergide.[3] Fibrothorax may also occur without a clear underlying cause, in which case it is known asidiopathic fibrothorax.
A technique calledpleurodesis can be used to intentionally create scar tissue within the pleural space, usually as a treatment for repeated episodes of a punctured lung, known as apneumothorax, or for pleural effusions caused bycancer. While this procedure usually generates only limited scar tissue, in rare cases a fibrothorax can develop.[6]
Fibrosis can affect one or both of the two layers of tissue forming thepleura—the visceral pleura adjacent to thelung and the parietal pleura adjacent to theribcage. The term fibrothorax implies severe fibrosis affecting both the visceral and the outer (parietal) pleura, fusing the lung to the chest wall.[2] The condition starts as an undrained pleural effusion. Over time, the undrained pleural effusion causes sustained inflammation of the pleura, which can then lead to deposition offibrin in the pleura and the development of a fibrotic scar. Eventually, a "peel" that is rich incollagen forms around the fluid collection. From this point, the illness can no longer be treated withthoracentesis, since the fluid will return to the cavity maintained by the peel.[4]
Over time, generally over the years, the fibrotic scar tissue slowly tightens and thickens, contracting the contents of one or both halves of the chest and reducing the mobility of the ribs. The peel can become deeper than 2 cm.[2] Within the chest, the lung is compressed and unable to expand (trapped lung), making it vulnerable tocollapse and causing breathlessness.[7] Restrictive lung disease from fibrothorax may occur when pleural fibrosis is so severe that it involves thediaphragm and ribcage and results primarily from decreased rib movement.[3]
At themicroscopic level, collagen fibres deposit in a basket weave pattern and form scar tissue.[7] Usually, the underlying condition has to cause intense inflammation of the pleura, though it is unclear exactly how this results in fibrosis. The precise mechanisms producing the fibrosis are not entirely clear. However, research indicates a protein called Transforming Growth Factor beta (TGF-β) plays a central role in producing fibrothorax.[3] Anti-TGF-β antibodies prevent fibrothorax in empyema in animal models.[3]
A fibrothorax can typically be diagnosed by taking an appropriate medical history in combination with the use of appropriate imaging techniques such as a plain chest X-ray or CT scan.[3] These imaging techniques can detect fibrothorax and pleural thickening that surround the lungs.[7] The presence of a thickened peel with or without calcification are common features of fibrothorax when imaged.[3] CT scans can more readily differentiate whether pleural thickening is due to extra fat deposition or true pleural thickening than X-rays.[3]
If a fibrothorax is severe, the thickening may restrict the lung on the affected side causing a loss of lung volume.[7] Additionally, themediastinum may be physically shifted toward the affected side.[3] A reduction in the size of one side of the chest (hemithorax) on an X-ray or CT scan of the chest suggests chronic scarring.[6] Signs of the underlying disease causing the fibrothorax are also occasionally seen on the X-ray.[6] ACT scan may show features similar to those seen on a plain X-ray.[7]Lung function testing typically demonstrates findings consistent withrestrictive lung disease.[6]
Conservative non-surgical treatment of fibrothorax is generally done by treating its underlying cause and is reserved for milder cases.Tobacco smoking cessation is strongly recommended since tobacco smoke exposure can worsen fibrosis.[9] Severe cases of fibrothorax may require supportivemechanical ventilation if the affected person is unable to breathe adequately on their own.[3]
In cases of fibrothorax caused by medication, it is recommended that the offending medications be stopped.Ergot alkaloid medications, which can worsen pleural fibrosis, are typically avoided.[3] Cases of fibrothorax attributable to medication typically stop worsening if the provoking medication is stopped.[3] In some situations, medication-induced fibrothorax improves after stopping the causative medication but fibrothorax usually does not completely resolve.[3]
Watchful waiting is appropriate for milder cases of fibrothorax in certain situations. Fibrothorax caused bytuberculosis,empyema, or haemothorax often improves spontaneously 3–6 months after the precipitating illness.Corticosteroids are commonly used to treat fibrothorax but are not well-supported by available evidence.[6]
In severe cases of fibrothorax that are compromising a person's ability to breathe, the scar tissue (fibrous peel) causing fibrothorax can be surgically removed using a technique calleddecortication.[1][7] However, surgical decortication is an invasive procedure which carries the risk of complications including a small risk of death,[7] and is therefore generally only considered if severe symptoms are present and have been for many months.[3] Surgical decortication is generally considered for people with fibrothoraces that are severe, causing significant shortness of breath, and have otherwise relatively healthy lungs since this enhances the likelihood of a better outcome.[3] Surgical removal of the pleura (pleurectomy) may be performed in refractory cases, as often happens whenasbestosis is the cause.[10]
Fibrothorax complicating another condition, such as tuberculouspleuritis, empyema, or acute haemothorax often spontaneously resolves in 3-6 months.[3]
The prognosis after surgical decortication is variable and depends on the health of the underlying lung before the procedure takes place.[3] If the lung was otherwise healthy, then certain aspects of lung function, such asvital capacity, may improve after decortication.[3] If, however, the lung had significant disease, then lung function often does not improve and may even deteriorate after such intervention.[3] The duration of fibrothorax does not affect prognosis.[3]
The mortality of surgery is less than 1% overall, but rises to 4-6% in the elderly. Other factors predicting poorer surgical outcomes include intraoperative complications, incomplete surgery, lung disease beyond the fibrothorax being treated, and specific causes of fibrothorax such as asbestosis.[10]
Sporadic cases are rarely reported in the medical literature, for example, due toiatrogenic or postoperative complications. Fibrothorax is rare in developed countries, mainly due to a lower incidence of tuberculosis. The condition is far more common in workers exposed to asbestos, with 5–13.5% of those exposed subsequently developing some degree of pleural fibrosis, sometimes not diagnosed until decades after the initial exposure.[9]