Pleural fibrosis J94.1

Pleural fibrosis is the focal or areal increase of the hyaline connective tissue fibres in the parietal and/or visceral pleura, which is usually accompanied by an adhesion of the two pleural leaves and obliteration of the pleural gap.

The connective tissue fibres sometimes extend deep into the lung parenchyma (radiologically recognizable as so-called crow's feet signs). The fibres calcify in the further course.

s. a. Pleural plaques

s.a. Asbestosis

s.a. pleural rind

After resorption of a pleural effusion in the case of asbestosis, for example, there is practically always an adhesion between the visceral and parietal pleura, which in approx. 50% of cases leads to the development of diffuse pleural fibrosis.

Men are more frequently affected by pleural fibrosis than women (occupational exposure). Fibrosis tends to affect older people (latency period).

Resorption of a pleural effusion virtually always results in adhesion of the visceral and parietal pleura. In about 50%, this adhesion leads to diffuse pleural fibrosis.

The most common cause of such effusions occurs in association with asbestos pleurisy. In this case, often only the parietal pleura is affected and both halves of the thorax are almost always altered by hyaline connective tissue fibers.

However, pleural fibrosis may also occur in the setting of hematothorax, empyema (in these cases, the visceral pleura is predominantly affected), or inhalation of various dusts.

Less frequently, pleural fibrosis is caused by fungal infection, radiotherapy, rheumatic diseases, or organized pleural effusions of other causes.

Fibrosis also occurs in the context of malignant diseases, such as mesothelioma, metastases, lymphoma or local bronchial carcinoma.

In malignant genesis, it is not uncommon for extensive pleural thickening to occur, ultimately leading to tethering of the lung. Such a fibrothorax is the most severe form of pleural fibrosis.

Depending on the extent of fibrosis, there is a more or less severe dyspnoea, which increases significantly under stress.

Sonography: Ultrasound shows a long distance, low-echo thickening which mainly affects both pleural leaves. In this case the pleural leaves are no longer distinguishable. The depth extension of such low-echo thickenings is usually less than 5 mm.

If there is also a pleural effusion, the pleural leaves can be separated from each other in this area. Occasionally, fibrin threads of varying sizes can be seen in the effusion.

In the scarred stage, the pleural leaves impress as a low-echo, solid and homogeneous thickening of the pleural gap. Calcifications are also possible. The pleural entry echo appears blurred and irregular. The lung no longer shows any respiratory displacement.

X-ray: The X-ray image often shows localized shadows between the pleural plates which correspond to calcifications. In addition, connective tissue structures extending deep into the lung parenchyma, so-called crow feet or comet's tail. These show a star-shaped convergence of scar tissue bands to a point located in the pleura. There are also peripherally located spherical atelectases which have broad-based contact with the pleura. Often diffuse pleural plaques are also detectable. The costophrenic angle may show homogeneous compression due to effusion formation or brightening when the pleural leaves are glued together.

Computer tomography: If no reliable differential diagnosis is possible, a CT is recommended.

Further examinations are usually not necessary.

Pulmonary function

In lung function, there is a reduction in lung volume and additional signs of a restrictive dysfunction, whereby the severity of the dysfunction can vary greatly depending on the extent of fibrosis.

Imaging procedures (see above)

For differentiation of a malignant process: In pleural fibrosis, the changes in the pleura are uniform and can be easily distinguished from the adjacent fatty tissue between the ribs and from the adjacent parietal pleura. The pleural leaves sometimes show calcifications. In malignant diseases, the pleural borders appear irregular to nodular and the adjacent fat is tumorously infiltrated.

• Mesothelioma
• Bronchial carcinoma

The therapy depends on the causative disease and also on the severity of the pleural fibrosis. Surgical measures (e.g. decortication) are indicated for fibrothorax or pleural rind.

Depending on the genesis and development of pleural fibrosis, the prognosis varies considerably.

It has been proven that the mesothelioma rate is increased after the development of pleural fibrosis. The prognosis for mesothelioma, on the other hand, is very unfavourable. The mean survival time is about 12 months.

In the part of the pleural fibrosis caused by asbestos exposure, the course is progressive in some patients, but also stationary in about 50 %.

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