Imaging of Occupational and Environmental Lung Diseases

Imaging diagnosis of pneumoconiosis with predominant nodular pattern: HRCT and pathologic findings

The radiological patterns of known pneumoconiosis have been changing in recent years. The basic pathology in pneumoconiosis is the presence of dust macules, mixed dust fibrosis, nodules, diffuse interstitial fibrosis, and progressive massive fibrosis. These pathologic changes can coexist in dust-exposed workers. High resolution CT reflects pathological findings in pneumoconiosis and is useful for the diagnosis. Pneumoconiosis such as silicosis, coal workers' pneumoconiosis, graphite pneumoconiosis, and welder's pneumoconiosis, has predominant nodular HRCT pattern. Diffuse interstitial pulmonary fibrosis is sometimes found in the lungs of this pneumoconiosis. In the early stages of metal lung, such as aluminosis and hard metal lung, centrilobular nodules are predominant findings, and in the advanced stages, reticular opacities are predominant findings. The clinician must understand the spectrum of expected imaging patterns related to known dust exposures and novel exposures. In this article, HRCT and pathologic findings of pneumoconiosis with predominant nodular opacities are shown.

Inhalational lung diseases

The term inhalational lung disease comprises a group of entities that develop secondary to the active aspiration of particles. Most are occupational lung diseases. Inhalational lung diseases are classified as occupational diseases (pneumoconiosis, chemical pneumonitis), hypersensitivity pneumonitis, and electronic-cigarette-associated lung diseases. The radiologic findings often consist of nonspecific interstitial patterns that can be difficult to interpret. Therefore, radiologists' experience and multidisciplinary teamwork are key to ensure correct evaluation. The role of the radiologist is fundamental in preventive measures as well as in diagnosis and management, having an important impact on patients' overall health. It is crucial to take into account patients' possible exposure to particles both at work and at home.

An Interesting Case of Mixed Dust Pneumoconiosis With Progressive Massive Fibrosis and Cor Pulmonale in a South American Farmer

Pneumoconiosis is an occupational disease found in workers with environmental exposure to organic and inorganic dust, as in mining, sandblasting, pottery, stone masonry, and farming. The inflammatory response of the lung to respirable dust causes the formation of macules, nodules, and fibrosis, and higher silica content in inhaled dust is associated with increased fibrosis. Mixed dust pneumoconiosis (MDP) is characterized by exposure to dust containing 10-20% silica, and its lung imaging show irregular opacities. Histopathology plays a vital role in the diagnosis of MDP. Though it has a favorable outcome, it evolves slowly over many years of constant exposure and is characterized by worsening dyspnea and cough gradually progressing to cor pulmonale. The only effective treatment is removing exposure, which makes it essential to recognize the disease early for a favorable outcome. We present a case of mixed dust pneumoconiosis in a farmer from South America who had asthma. He presented with worsening dyspnea and multiple nodules in both lungs on imaging and cor pulmonale. An extensive workup was done, and it ruled out any malignancy and tuberculosis. Analysis of video-assisted thoracoscopic surgery (VATS) biopsy samples confirmed the diagnosis of mixed dust pneumoconiosis. He had a confluence of irregular nodes in the upper lobes of the lungs, and the largest was 2.1 cm. This fits the International Labour Organization (ILO) definition of progressive massive fibrosis. This, along with cor pulmonale present in him, gives it a poor prognosis even after he is removed from dust exposure. He received steroids, which led to symptomatic improvement, and he was discharged to follow up with the pulmonologist.

Imaging diagnosis of classical and new pneumoconiosis: predominant reticular HRCT pattern

Our understanding of the manifestations of pneumoconioses is evolving in recent years. Associations between novel exposures and diffuse interstitial lung disease have been newly recognized. In advanced asbestosis, two types of fibrosis are seen, probably related to dose of exposure, existence of pleural fibrosis, and the host factor status of the individual. In pneumoconiosis of predominant reticular type, nodular opacities are often seen in the early phase. The nodular pattern is centrilobular, although some in metal lung show perilymphatic distribution, mimicking sarcoidosis. High-resolution computed tomography enables a more comprehensive correlation between the pathologic findings and clinically relevant imaging findings. The clinician must understand the spectrum of characteristic imaging features related to both known dust exposures and to historically recent new dust exposures.

Domestic mixed-dust pneumoconiosis: A case report and literature review

Background

Mixed-dust pneumoconiosis (MDP) is a controversial disease with respect to diagnostic criteria. Usually, it is regarded as an occupational disease, but cases due to domestic exposure have been reported. In domestic settings, different dust sources may contribute individually or collectively to the pathogenesis.

Case presentation

A 56-year-old woman presented with chest nodularity on chest X-ray examination that had not resolved after 6 months of tuberculosis (TB) treatment. Her history showed significant exposure to mixed dusts caused by grinding grains with stones and the use of biomass fuel.

Conclusion

In residential settings, sufficient exposure to a variety of dusts, primarily silica-based dusts as well as those containing other less-fibrogenic materials, such as carbon, silicates and iron, have been shown to cause mixed-dust pneumoconiosis. In settings where the incidence of TB is very high, such as South Africa, the diagnosis of MDP might be overlooked due to the similarities of both diseases in their radiological presentations, especially when a detailed history of domestic exposure is omitted.

Imaging of Occupational Lung Disease

Occupational lung diseases span a variety of pulmonary disorders caused by inhalation of dusts or chemical antigens in a vocational setting. Included in these are the classic mineral pneumoconioses of silicosis, coal worker's pneumoconiosis, and asbestos-related diseases as well as many immune-mediated and airway-centric diseases, and new and emerging disorders. Although some of these have characteristic imaging appearances, a multidisciplinary approach with focus on occupational exposure history is essential to proper diagnosis.

The comparison of high-resolution computed tomography findings in asbestosis and idiopathic pulmonary fibrosis

BACKGROUND

To determine whether the HRCT findings are useful to differentiate asbestosis from idiopathic pulmonary fibrosis (IPF).

METHODS

We assessed HRCT scans from patients with asbestosis (n = 96) and IPF (n = 65). The frequencies and extent of parenchymal abnormalities and the frequencies of pleural changes were evaluated by consensus of two chest radiologists.

RESULTS

There was a significant difference between IPF and asbestosis in pleural changes. In addition, there were significant differences between IPF and asbestosis in several parenchymal abnormalities on CT, especially in the less advanced stage of both diseases. On multivariate analysis, HRCT features that distinguished asbestosis from IPF were subpleural lines at a distance of less than 5 mm from the inner chest wall, subpleural dots and parenchymal bands.

CONCLUSIONS

There are significant differences between IPF and asbestosis in the parenchymal and pleural abnormalities on CT.

Imaging in occupational and environmental lung disease

PURPOSE OF REVIEW

Work-related and environmental lung disease is increasing over time and new antigens causing pulmonary response are described in medical literature every year with more or less specific imaging findings. The purposes of this review are to highlight the current role of imaging, describe classic as well as uncommon high-resolution computed tomography (HRCT) patterns helpful in guiding diagnosis and update the recent literature on this topic.

RECENT FINDINGS

Recent literature on imaging of occupational and environmental lung disease is scarce and is predominantly based on the HRCT appearance related to specific antigen exposure and on prognostic significance of findings.

SUMMARY

Knowledge of imaging modality potential and radiologic appearance may guide identification, characterization and follow-up of old and new occupational and environmental lung diseases. HRCT plays a key role in this context, having radiation exposure as a major limitation, especially in asymptomatic patients. Low-dose HRCT has the potential to be employed for screening and surveillance of the exposed individuals. However, future research is needed to further this field.

Pneumoconiosis and respiratory problems in dental laboratory technicians: analysis of 893 dental technicians

OBJECTIVES

To explore the rate of pneumoconiosis in dental technicians (DTP) and to evaluate the risk factors.

MATERIAL AND METHODS

Data of 893 dental technicians, who were admitted to our hospital in the period January 2007-May 2012, from 170 dental laboratories were retrospectively examined. Demographic data, respiratory symptoms, smoking status, work duration, working fields, exposure to sandblasting, physical examination findings, chest radiographs, pulmonary function tests and high-resolution computed tomography results were evaluated.

RESULTS

Dental technicians' pneumoconiosis rate was 10.1% among 893 cases. The disease was more common among males and in those exposed to sandblasting who had 77-fold higher risk of DTP. The highest profusion subcategory was 3/+ (according to the International Labour Organization (ILO) 2011 standards) and the large opacity rate was 13.3%.

CONCLUSIONS

To the best of our knowledge, it was the largest DTP case series (N = 893/90) in the literature in English. Health screenings should be performed regularly for the early diagnosis of pneumoconiosis, which is an important occupational disease for dental technicians.

[What are the tools for post-occupational follow-up, how should they be performed and what are their performance, limits and benefit/risk ratio? Chest X-Ray and CT scan]

Chest radiography and computed tomography (CT) are the two radiological techniques used for the follow-up of people exposed to asbestos. Since the last conference of consensus (1999), the scientific literature has primarily covered high-resolution CT and high-resolution volume CT (HR-VCT). We consider in turn the contribution of digital thoracic radiography, recommendations for the performance of HR-VCT to ensure the quality of examination while controlling the delivered radiation dose, and the need to refer to the "CT atlas of benign diseases related to asbestos exposure", published by a group of French experts in 2007, for interpretation. The results of the published studies concerning radiography or CT are then reviewed. We note the great interobserver variability in the recognition of pleural plaques and asbestosis, indicating the need for adequate training of radiologists, and the importance of defining standardized, quantified criteria for CT abnormalities. The very low agreement between thoracic and general radiologists must be taken into account. The reading of CT scans in cases of occupational exposure to asbestos should be entrusted to thoracic radiologists or to general radiologists having validated specific training. A double interpretation of CT could be considered in medicosocial requests. CT is more sensitive than chest radiography in the detection of bronchial carcinoma but generates a great number of false positive results (96 to 99%). No scientific data are available to assess the role of imaging by either CT or chest radiography in the early detection of mesothelioma.