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Mesothelioma and asbestos-related pleural diseases

Thursday, July 31, 2008

Source: Respiration: International Review Of Thoracic Diseases

The journal Respiration: International Review of Thoracic Diseases has recently published an overview of mesothelioma and a number of other diseases caused by asbestos exposure. The article specifically covers the pleural conditions that exposure causes, so asbestos-related diseases that affect only the lungs, such as lung cancer and asbestosis, were excluded. After giving a brief introduction to the use of asbestos and the various types of fibers included in its definition, they cover four of the non-malignant conditions that have been linked to the fibers, as well as a review of the current knowledge regarding pleural mesothelioma.

This article is a summary of their article with a focus on the non-malignant diseases, as we have cover mesothelioma extensively throughout the site.

Introduction to Asbestos

The authors note that asbestos has been used for centuries, but it wasn’t until the 19th century that advances in the ability to process it enabled the large scale, general use that continued through much of the 20th century. The development of techniques that allowed the fibers to be spun and weaved into various forms led to their use in products as diverse as brake linings and cement.

Sadly, this large scale use is what led to the development of diseases specific to exposures to the fibers. Asbestos-related diseases now make-up an entire class of medical conditions. While lung cancer and mesothelioma are by the far the worst of these diseases, a number of other conditions can also lead to pain and trouble breathing. The following four pleural conditions are directly linked to asbestos exposure: benign asbestos pleural effusion (BAPE), pleural plaques, diffuse pleural thickening (DPT) and rounded atelectasis.

Benign Asbestos Pleural Effusion (BAPE)

Benign asbestos pleural effusions are non-malignant effusions that commonly occur within twenty years of asbestos exposure. The authors describe BAPE as “an effusion that occurs in the setting of asbestos exposure, in the absence of other conditions and is not followed by the development of malignancy within three years.” Thus, BAPE is a diagnosis given in the absence of more serious conditions. Whenever a patient presents with a pleural effusion a full round of tests should be conducted to rule out malignant conditions.

BAPEs commonly appear within 20 years of a person’s exposure to asbestos, but like many of the other asbestos-related diseases, a longer latency period is not out of the question. A BAPE is not a particularly dangerous condition and most people who develop one do not require treatment, but some individuals will present with large effusions that require draining.

The authors note that BAPEs are not themselves indicative of a future malignant development, but they do share a common causative ancestor to mesothelioma (and lung cancer).

Pleural Plaques

It is well known in medical circles that pleural plaques are a common development in asbestos-exposed individuals. Pleural plaques are a type of fibrosis that arises in the parietal pleura, typically 20-30 years after asbestos exposure. Epidemiological studies have demonstrated that pleural plaques are quite rare in non-asbestos-exposed populations and are found in a small number of people with environmental exposure to the fibers, but that their incidence greatly increases in individuals with occupational exposures to asbestos.

Many cases of pleural plaques are not symptomatic, but a subset of patients will experience restricted pulmonary function. Pleural plagues, like BAPEs, are a non-malignant condition and their development is not indicative of a future malignancy.

Diffuse Pleural Thickening (DPT)

Diffuse pleural thickening (DPT) is another condition that can be related to asbestos exposure, but is not solely caused by asbestos. It is a fibrosis of the visceral pleura that leads to its fusion with the parietal pleura. Among those exposed to asbestos, DPT is less common than pleural plaques, but—unlike pleural plagues—it is often associated with serious pulmonary symptoms, including chest pain and “significant restrictive ventilatory impairment.”

Rounded Atelectasis

Rounded atelectasis is another pleural disease that is strongly linked to asbestos exposure, even though it is less common than either pleural plaques or DPT. It affects the visceral pleura and can be confused with primary lung cancer during radiological analysis. The condition is also known as folded lung, asbestos pseduotumor, or Blesovsky syndrome.

Malignant Mesothelioma

As we have covered extensively on this site, malignant mesothelioma is the most serious asbestos-caused disease because there is no cure for it. Even as very isolated cases of significant survival have appeared in the literature, the disease is still associated with a median survival time of under 16 months.

To learn more about mesothelioma, we suggest you read the following articles: pleural mesothelioma, peritoneal mesothelioma, mesothelioma treatments.

Labels: asbestos, mesothelioma

posted by Belluck & Fox at 11:22 AM
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