Asbestos-related diseases

Asbestos-related diseases include:
 * 1) non-malignant diseases: asbestosis, pleural plaques, acute pleurisy;
 * 2) malignant diseases: bronchogenic carcinoma, malignant pleural peritoneal mesothelioma, laryngeal a ovarian carcinoma.

Noxa characteristics
Asbestos is a group of minerals (silicates) that exist in two forms – serpentines a amfiboles. Their common feature is a fibrous structure, with long and thin fibers. The fibers are nonflammable and resistant to acids and alkalis;


 * 1) serpentine fibers – chrysotile („white asbestos“),
 * 2) * long, flexible, twisted, intertwined (used in textile processing, the only asbestos that is industrially produced is chrysotile),
 * 3) * bearings – Canada, the Urals, Cyprus, South African Republic,
 * 4) amfibole fibers – 5 types: crocidolite („blue asbestos“), amosite, anthophyllite, actinolite, tremolite,
 * 5) * shorter, brittle, very resistant to acids.

Occupational exposure

 * During mining, during transport (less common nowadays - it is packed in plastic),
 * during processing,
 * usage – asbestos-cement materials, roofing (eternit), pipes, cladding boards, textiles (protective clothing for firefighters and metallurgical workers), friction and braking equipment (formerly used to make brake pads).

Pleurální hyalinóza
Demarcated pleural plaques, diffuse pleural thickening. Direct local response to the presence of asbestos fibers in the pleural cavity. They get out of the alveolus through the lymphatic system, the fibers injure the pleura → inflammation, hemorrhage → organization → adhesions.
 * Pleural plaques – demarcation of the hyaline fibrosis lesion - especially in the submesothelial layer of the parietal pleura posterolaterally, irregular shape and size, white-ish glossy surface, prominent, they calcify irregularly and form bizarre shapes (pleuritis calcarea).
 * Diffuse pleural thickening – affects mostly the visceral pleura, tends to have the character of a milky spot, forms adhesions between the pleurae, fibrosis permeates the lung parenchyma and interlobar spaces.

Clinical picture
Demarcated plaques are the most common manifestation of asbestos exposure. They are often an accidental X-ray finding, enlarge over time, tend to calcify and do not cause problems. Diffuse pleural damage - most often after undergoing acute pleurisy with effusion, affects most of the pleura. It usually spreads bilaterally, from the apex to the base.

Extensive plaques lead to exertional dyspnea, irritating cough, persistent chest pain.

Diagnostic criteria
Pleural fibrosis that is at least 50 mm wide, 80 mm long, 3 mm thick (on a CT). Around it is rounded atelectasis, blending of the lesions into the parenchyma on a CT is described as crow's feet.

Examination methods

 * Chest X-ray – bizarre demarcated shadows,
 * diffuse thickening – general obscuration of the lung pattern,
 * CT, HRCT,
 * pulmonary function - restriction.

Acute pleurisy
Local reaction to the presence of asbestos on the pleura. It is asymptomatic in two thirds, the exudate does not exceed 500 ml and is usually absorbed spontaneously.

Breathing difficulties, cough, weakened breathing, fremitus pectoralis disappeares.

Examination
X-ray, ultrasonography, thoracic puncture.

Bronchogenic carcinoma
Carcinogenicity depends on the amount, time and length of the fiber (above 5), it is an epigenetic carcinogen (IARC group I). It is involved in the development of all types of bronchogenic carcinoma - squamous cell, small cell, undifferentiated large cell and adenocarcinoma. The risk of [[smoking] and asbestos is multiplied (exposed smokers - 50-90 times higher chances than unexposed non-smokers).

Malignant pleural and peritoneal mesothelioma
It is a causal relationship. Mesothelioma practically doesn´t develop without asbestos exposure, amphiboles are a 10 times greater risk.

Pathology
They can be localized or diffuse. Localized mesothelioma can expand and fill the entire hemithorax, diffuse mesothelioma is multiple. The gray nodules on the pleura merge to form tumorous masses. Usually there is a hemorrhagic pleural effusion, the tumor overgrows the lungs, grows into the surroundings - chest wall, mediastinum, abdomen...

Clinical picture
Persistent pain, exertional dyspnoea (sometimes the first symptom is significant resting dyspnea due to the effusion). In inflammatory effusion, the pain stops when the pleurae move away from each other, here it usually does not stop. Weight loss, subfebrile temperature, symptoms of tumor organ damage.

Latency - 30-40 years, cigarette smoking has no effect on the course. Progresses very rapidly despite treatment, most patients die within a year of diagnosis.

Examination

 * X-ray – thickening of the pleura, extensive effusion or signs of another asbestos disease,
 * CT, HRCT,
 * exudate examination, pleura cytology,
 * the occupational risk of mesothelioma is strongly underestimated in our country.

Prevention
The import, production and distribution of amphibole fibers are currently banned in the Czech Republic and usage is restricted.

Therapy
There is no causal treatment for these conditions. Oxygen therapy, bronchodilation in COPD.