Minimal pathologic changes of the lung and asbestos exposure

Asbestos burden in lungs of mesothelioma patients with pleural plaques, lung fibrosis and/or ferruginous bodies at histology: a postmortem SEM-EDS study

The causal attribution of asbestos-related diseases to past asbestos exposures is of crucial importance in clinical and legal contexts. Often this evaluation is made based on the history of exposure, but this method presents important limitations. To assess past asbestos exposure, pleural plaques (PP), lung fibrosis and histological evidence of ferruginous bodies (FB) can be used in combination with anamnestic data. However, such markers have never been associated with a threshold value of inhaled asbestos. With this study we attempted to shed light on the dose-response relationship of PP, lung fibrosis and FBs, investigating if their prevalence in exposed individuals who died from malignant mesothelioma (MM) is related to the concentration of asbestos in lungs assessed using scanning electron microscopy equipped with energy dispersive spectroscopy. Moreover, we estimated the values of asbestos concentration in lungs associated with PP, lung fibrosis and FB. Lung fibrosis showed a significant positive relationship with asbestos lung content, whereas PP and FB did not. We identified, for the first time, critical lung concentrations of asbestos related to the presence of PP, lung fibrosis and FB at histology (respectively, 19 800, 26 400 and 27 400 fibers per gram of dry weight), that were all well-below the background levels of asbestos identified in our laboratory. Such data suggest that PP, lung fibrosis and FB at histology should be used with caution in the causal attribution of MM to past asbestos exposures, while evaluation of amphibole lung content using analytical electron microscopy should be preferred.

The pathologist's view of silicosis in 1930 and in 2015. The Johannesburg Conference legacy

The 1930 International Labour Office Conference on silicosis in Johannesburg was a turning point in the history of silicosis and in the recognition of the associated pathologic patterns. Since 1930, pneumoconioses such as silicosis have become much rarer in developed countries and can now be diagnosed at an early stage based on clinical and radiologic criteria. However, in spite of these advances, pathologists must remember to look for silica in tissues, particularly when clinical and radiologic findings are more uncertain. Furthermore, nowadays pathologists essentially observe silicotic lesions as incidental findings adjacent to lung cancers. In addition to identifying the characteristic lesions, pathologists must also try to identify their causative agent, in the case of crystalline silica firstly by using polarized light examination, followed as appropriate by more sophisticated devices. Finally, pathologists and clinicians must always keep in mind the various implications of exposure to silica compounds in a wide range of diseases.

Commentary on pathologic diagnosis of asbestosis and critique of the 2010 Asbestosis Committee of the College of American Pathologists (CAP) and Pulmonary Pathology Society's (PPS) update on the diagnostic criteria for pathologic asbestosis

We reviewed the 2010 Asbestosis Committee's update on the diagnostic criteria for pathologic asbestosis. We must respectfully disagree with many of the criteria set forth therein, especially for recognizing asbestosis at its earliest stages; with statements focusing on the number of asbestos bodies needed in order to make a pathologic diagnosis of asbestosis; and regarding the benefits and pitfalls of relying on fiber analysis for diagnostic purposes, especially where chrysotile asbestos is concerned, including the methodology used for fiber determination. This critique has become even more relevant with the 2014 Helsinki criteria publication, which adopted the 2010 CAP/PPS criteria. Based on our review of these newer criteria and our experience in this field, we find that the CAP-NIOSH 1982 criteria is still the most acceptable method for the pathologic diagnosis and grading of asbestosis, which can be described as pulmonary fibrosis caused by inhalation of asbestos fibers.

Patterns of pulmonary dysfunction in asbestos workers: a cross-sectional study

BACKGROUND

Restrictive patterns of pulmonary function abnormalities associated with asbestos exposure are well described. Studies are less consistent, however, regarding the association of asbestos inhalation with airway dysfunction and obstructive impairment.

METHODS

We compared pulmonary function test results between 277 chrysotile exposed workers (22% non-smokers) and 177 unexposed controls (50.3% non-smokers). Information on exposure and smoking were collected using a standardized questionnaire. Standardized spirometric and DCLO Measurement methods were utilized. CXRs were read based on ILO pneumoconiosis guidelines.

RESULTS

Asbestos exposed subjects had significantly reduced FVC, FEV1, FEV1/FVC and DLCO. Restricting the analysis to non-smokers, asbestos workers still had about 3% lower FEV1/FVC ratio than controls, but this difference did not reach statistical significance. Among exposed workers, the presence of radiographic evidence of asbestosis further lowered FVC and DLCO but not FEV1/FVC compared to asbestos exposure without radiographic asbestosis. Additionally, smoking asbestos workers had significantly lower DLCO compared to non-smoking workers.

CONCLUSION

Asbestos exposure, especially when radiographic evidence of interstitial fibrosis from asbestosis is present, leads to significant decreases in FVC, FEV1 and the DLCO. However, asbestos exposure alone is not significantly associated with a reduction of the FEV1/FVC. Smoking-asbestos workers had significantly lower DLCO than their non-smoking counterparts. Whether asbestos interacts with smoking additively or synergistically on DLCO needs further investigation. Similarly, further studies are needed to assess the progression and clinical significance of asbestos induced airway dysfunction.

Grand rounds: asbestos-related pericarditis in a boiler operator

CONTEXT

Occupational and environmental exposures to asbestos remain a public health problem even in developed countries. Because of the long latency in asbestos-related pathology, past asbestos exposure continues to contribute to incident disease. Asbestos most commonly produces pulmonary pathology, with asbestos-related pleural disease as the most common manifestation. Although the pleurae and pericardium share certain histologic characteristics, asbestos-related pericarditis is rarely reported.

CASE PRESENTATION

We present a 59-year-old man who worked around boilers for almost 30 years and was eventually determined to have calcific, constrictive pericarditis. He initially presented with an infectious exacerbation of chronic bronchitis. Chest radiographs demonstrated pleural and pericardial calcifications. Further evaluation with cardiac catheterization showed a hemodynamic picture consistent with constrictive pericarditis. A high-resolution computerized tomography scan of the chest demonstrated dense calcification in the pericardium, right pleural thickening and nodularity, right pleural plaque without calcification, and density in the right middle lobe. Pulmonary function testing showed mild obstruction and borderline low diffusing capacity.

DISCUSSION

Based on the patient's occupational history, the presence of pleural pathology consistent with asbestos, previous evidence that asbestos can affect the pericardium, and absence of other likely explanations, we concluded that his pericarditis was asbestos-related.

RELEVANCE TO CLINICAL PRACTICE

Similar to pleural thickening and plaque formation, asbestos may cause progressive fibrosis of the pericardium.

The attribution of lung cancers to asbestos exposure: a pathologic study of 924 unselected cases

We studied a series of 924 nonselected surgical cases of lung carcinoma (without occupational history in clinical records) by histologic examination and light microscopic determination of asbestos body (AB) concentration to determine cancers attributable to asbestos exposure. Lower lobes showed higher concentrations, but no significant associations were recorded between concentrations and histologic type of the lung carcinomas. Histologic asbestosis was demonstrated in 56 cases considered definitely asbestos-related. In 12 of them, the demonstration of asbestosis was attained only after repeated examination of additional sections, suggested by thefinding of more than 1,000 ABs per gram of dry weight (gdw), an indicator of occupational asbestos exposure. In the 56 cases, the media

Asbestos body burden in decomposed human lungs

The authors discuss the influence of postmortem tissue decomposition on the lung asbestos body (AB) burden, with the aim of evaluating the reliability of data obtained from autopsies performed for medicolegal purposes several months after deaths in possible connection with asbestos-related pathology. Eight autopsy cases were selected, each one with occupational exposure considered very probable on the basis of the history or pathologic findings. In each case the AB concentrations were assessed soon after death in one lung and after periods of 1 to 18 months in the others, which had been stored in sealed containers without fixation. AB concentrations consistently decreased with time in rotten lungs. The counts in some cases became negative a few months after death, even in cases with very high AB counts at first examination. It may be reasonably inferred that, in putrefied lungs from corpses exhumed after months of internment, the counts in digested tissues and the screening of histologic sections for AB may give false-negative results.

Asbestos lung burden and asbestosis after occupational and environmental exposure in an asbestos cement manufacturing area: a necropsy study

OBJECTIVE

The largest Italian asbestos cement factory had been active in Casale Monferrato until 1986: in previous studies a substantial increase in the incidence of pleural mesothelioma was found among residents without occupational exposure to asbestos. To estimate exposure to asbestos in the population, this study evaluated the presence of histological asbestosis and the lung burden of asbestos fibres (AFs) and asbestos bodies (ABs).

METHODS

The study comprises the consecutive series of necropsies performed at the Hospital of Casale Monferrato between 1985 and 1988. A sample of lung parenchima was collected and stored for 48 out of 55 necropsies. The AF concentration was measured with a TEM electron microscope with x ray mineralogical analysis. The ABs were counted and fibrosis evaluated by optical microscopy. The nearest relative of each subject was interviewed on occupational and residential history. Mineralogical and histological analyses and interviews were conducted in 1993-4.

RESULTS

Statistical analyses included 41 subjects with AF, AB count, and interview. Subjects without occupational exposure who ever lived in Casale Monferrato had an average concentration of 1500 AB/g dried weight (gdw); Seven of 18 presented with asbestosis or small airway lung disease (SAL). G2 asbestosis was diagnosed in two women with no occupational asbestos exposure. One of them had been teaching at a school close to the factory for 12 years. Ten subjects had experienced occupational asbestos exposure, seven in asbestos cement production: mean concentrations were 1.032 x 10(6) AF/gdw and 96,280 AB/gdw. Eight of the 10 had asbestosis or SAL.

CONCLUSION

The high concentration of ABs and the new finding of environmental asbestosis confirm that high asbestos concentration was common in the proximity of the factory. Subjects not occupationally exposed and ever living in Casale Monferrato tended to have higher AB concentration than subjects never living in the town (difference not significant). The concentrations of ABs and AFs were higher than those found in other studies on nonoccupationally exposed subjects.

Localized inflammatory pulmonary disease in subjects occupationally exposed to asbestos

In reviewing pathology materials from patients occupationally exposed to asbestos, we identified eight patients with either localized nodules in their lung or unusual pathologic changes. The chest radiographs of six patients showed isolated parenchymal nodules thought to represent primary neoplasms. In three cases, pathologic examination of these nodules showed intraluminal fibrosis and inflammation of the distal airways, a pattern of change frequently referred to as "bronchiolitis obliterans organizing pneumonitis." In each instance, asbestos bodies were present in association with the fibroinflammatory tissue. In one case, the nodule showed a desquamative interstitial pneumonitis type pattern, and asbestos bodies were present admixed with the alveolar macrophages and occasionally within their cytoplasm. In one case, the nodule was composed of nonspecific inflammation and fibrosis with focal bronchiolitis obliterans and frequent asbestos bodies scattered throughout the area of inflammation and fibrosis, and in another case, necrotizing inflammation association with Aspergillus fungal organisms was identified. Granulomatous inflammation was the dominant pulmonary pathologic change in one patient, and the other patient's lung biopsy specimen showed a diffuse lymphocyte-plasma cell interstitial pneumonitis. The cases reported suggest that asbestos may cause localized lesions in the lung that clinically and radiographically are misinterpreted as cancer and that pathologically show inflammation and fibrosis of the distal airways. In addition, our observations suggest that asbestos may cause granulomatous inflammation, a desquamative interstitial type pneumonitis, and a lymphocytic interstitial pneumonitis type pattern. Our conclusions that asbestos may cause these pathologic changes are supported by case reports in the clinical and pathologic literature, clinicopathologic studies, and by experimental studies.