High-resolution computed tomography in cases with environmental exposure to asbestos in Turkey

Thoracic computed tomography findings in malignant mesothelioma

Background

Malignant pleural mesothelioma (MPM) is an uncommon neoplasm. MPM occurs more frequently in patients born or living in certain villages of Turkey.

Objectives

We aimed to review radiological findings of MPM.

Patients and Methods

We reviewed the CT findings in 219 biopsy-proven MPM patients admitted to our clinic between 1993 and 2008.

Results

The most common CT findings included pleural thickening (n=197, 90%) classified as diffuse (n=138, 63%), nodular (n=49, 22%) and mass-type (n=16, 7%). Pleural effusion was found in 173 patients (79%), involvement of the interlobar fissures in 159 (73%), mediastinal pleural involvement in 170 (78%), volume contraction in 142 (65%), mediastinal shift in 102 (47%) and mediastinal lymphadenopathy in 54 (25%).

Conclusion

MPM may present with diverse radiological features. Pleural thickening and pleural effusion were the most frequent radiological findings. Thoracic CT scans might be assessed more cautiously in patients with environmental exposure to asbestos.

The health impact of nonoccupational exposure to asbestos: what do we know?

The objective of this study was to examine the epidemiological data that confirm the risks of pleural mesothelioma, lung cancer, and other respiratory damage associated with nonoccupational exposure to asbestos, in circumstances where exposure levels are usually lower than those found in the workplace: domestic and paraoccupational exposure to asbestos-containing material among people living with asbestos workers or near asbestos mines and manufacturing plants, environmental exposure from naturally occurring asbestos in soil, and nonoccupational exposure to asbestos-containing material in buildings. Studies concerning natural asbestos in the environment show that the exposure that begins at birth does not seem to affect the duration of the latency period, but the studies do not show whether early exposure increases susceptibility; they do not suggest that susceptibility differs according to sex. Solid evidence shows an increased risk of mesothelioma among people whose exposure comes from a paraoccupational or domestic source. The risk of mesothelioma associated with exposure as result of living near an industrial asbestos source (mines, mills, asbestos processing plants) is clearly confirmed. No solid epidemiological data currently justify any judgment about the health effects associated with passive exposure in buildings containing asbestos. Most of the studies on nonoccupational sources reported mainly amphibole exposure, but it cannot be ruled out that environmental exposure to chrysotile may also cause cancer. Nonoccupational exposure to asbestos may explain approximately 20% of the mesotheliomas in industrialized countries, but it is does not seem possible to estimate the number of lung cancers caused by these circumstances of exposure.

The usefulness of computed tomography in detecting asbestos-related pleural abnormalities in people who had indeterminate chest radiographs: the Libby, MT, experience

This epidemiological study was conducted to determine whether high-resolution computed tomography (HRCT) is useful to screen for pulmonary abnormalities in people exposed to vermiculite containing asbestos. During June-September 2001, we evaluated HRCT of 353 people in Libby, MT, who had been exposed to asbestiform minerals associated with vermiculite. Of these, 334 participants of the summer 2000 medical testing program underwent HRCT of the chest at St. John's Lutheran Hospital and 19 eligible people who recently had undergone an HRCT scan at the same facility and under the same testing protocol allowed the study reviewers to use that scan. All 353 study participants were former vermiculite mine/mill workers (n = 55), their household contacts (n = 99), and people exposed to vermiculite through recreational or other activities (n = 199). Participants' 2000 medical testing results indicated only one of the three B-reader chest radiograph reviewers had reported a pleural abnormality (indeterminate chest radiograph). Three expert computer tomography (CT) scan evaluators reviewed the HRCT scans and identified pleural abnormalities in 98 (27.8%) of the 353 participants whose previous chest radiographs were classified indeterminate. Of these 98 people, 69 (70.4%) were either former vermiculite mine/mill workers or household contacts, and 40 (40.8%) showed pleural calcification on HRCT. Thirty out of the 40 people with pleural calcification reported having no occupational exposure to either Libby vermiculite or asbestos. Our findings indicate that low-dose HRCT can be considered for screening certain former vermiculite mine/mill workers and their household contacts who have indeterminate chest radiographs and may be useful for diagnosing a suspicious finding on a chest radiograph, particularly in a high-risk person.

Benign asbestos pleural diseases

The global incidence of asbestos-related lung diseases is expected to continue to rise. Although much attention is devoted to malignant diseases induced by asbestos, benign asbestos pleural diseases (pleural plaques, benign asbestos-related pleural effusion, diffuse pleural thickening, and rounded atelectasis) are common in clinical practice and often produce diagnostic difficulties. The authors describe the clinical features of benign asbestos-related pleural disease, before focusing on recent advances in radiology and on controversies surrounding the pathogenesis of asbestos-induced pleural injury. Advances in computed tomography have assisted the understanding and diagnosis of these diseases, and increasing evidence suggests radiologic appearances on computed tomography can predict impairment in pulmonary function tests. The pathogenesis of asbestos-induced pleural diseases has also been subject to extensive investigation. Asbestos fibers can provoke pleural inflammation from direct toxicity to mesothelial cells. Inhaled asbestos fibers can also elicit pleural injury indirectly via the release of growth factors and inflammatory cytokines from within the lung. Although progress has been made in the understanding of the mechanisms of asbestos pleural injury, many important questions remain unanswered. The role of genetic factors and possible environmental cofactors (eg, simian virus 40) in the pathogenesis of benign asbestos pleural diseases requires further research.

Observer variation in computed tomography of pleural lesions in subjects exposed to indoor asbestos

To assess the reliability of computed tomography (CT) in detecting discrete pleural lesions, the interobserver and intra-observer variability in reading the conventional and high-resolution CT (HRCT) scans of 100 volunteers, who had worked for > or = 10 yrs in a building with known asbestos contamination, was evaluated. In the first session, pleural abnormalities were detected by a single radiologist (A1) in 13 subjects. In the second session, the scans were read again independently by the same radiologist (A2) and two other experienced radiologists (B, C). The final decision for the presence of pleural lesions was made in a final consensus reading. This gave a diagnosis of pleural abnormalities in 18 subjects, of whom eight (44%) had been detected by all three readers, five (28%) by two readers and four (22%) by only one reader; one scan, rated normal by all readers during the second session, was reconsidered because pleural abnormalities had been noted at the first reading (A1). The intra-observer agreement for reader A was good (kappa (kappa) 0.68) but the interobserver agreement between the readers was only fair to moderate (weighted kappa: A2-B=0.43, A2-C = 0.45, B-C = 0.26) in the second reading session. In conclusion, when looking for the prevalence of pleural lesions in indoor asbestos exposed subjects, the potential lack of consistency in reporting the presence of small pleural abnormalities must be borne in mind and strict precautions must be taken.

Comparison of the effectiveness of some pleural sclerosing agents used for control of effusions in malignant pleural mesothelioma: a review of 117 cases

BACKGROUND AND OBJECTIVES

Management of malignant pleural mesothelioma (MPM) has been an important clinical issue regardless of the treatment modality employed. We aimed to investigate the efficacy of oxytetracycline (OT), Corynebacterium parvum (CP), and nitrogen mustard (NM) in the management of pleural effusion associated with MPM.

METHODS

One hundred and seventeen patients who had stage-2 MPM or over according to the Butchart staging system and unilateral or bilateral pleural effusion took part in the study. The patients received either OT (35 mg/kg), CP (7 mg), or NM (0.4 mg/kg) through a chest tube for pleurodesis. The association between several clinical parameters and patient survival was also investigated.

RESULTS

OT was applied to 59, CP to 29 and NM to 29 cases. A statistical analysis of the results obtained by these agents have demonstrated that OT (30 days, 81%; 90 days, 76.2%) and CP (30 days, 86.2%; 90 days, 79.3%) led to a significantly higher rate of successful pleurodesis as compared to NM (30 days, 48.2%; 90 days, 41.3%; p <0.05). Although the procedure was generally well tolerated by the patients, the NM-treated group experienced significantly more nausea-vomiting (46.1%) and hypotension (35.8%) compared to patients who received OT (nausea-vomiting and hypotension 4.3%; p < 0.001) and CP (nausea-vomiting and hypotension 5.1%; p < 0.001). Furthermore, we found that thrombocytosis, chest pain and weight loss were significantly associated with poor prognosis, whereas epithelial type had a positive effect on survival.

CONCLUSION

These results suggest that OT and CP may be used as effective sclerosing agents for pleurodesis in the control of pleural effusions associated with MPM, without major side effects.

Malignant pleural mesothelioma caused by environmental exposure to asbestos in the Southeast of Turkey: CT findings in 117 patients

BACKGROUND AND OBJECTIVES

Malignant pleural mesothelioma (MPM) is reported to be common in the southeast of Turkey, as a result of environmental asbestos exposure. The aim of this study was to evaluate the computed tomography (CT) features of MPM in patients with a history of asbestos exposure.

METHODS

The CT scans of 117 patients who had a diagnosis of MPM were retrospectively evaluated. Additionally, CT findings of histologic subtypes were compared.

RESULTS

The most common CT findings included pleural effusion (n = 104, 89%), pleural thickening (n = 96, 82%), mediastinal pleural involvement (n = 77, 66%) and interlobar fissural involvement (n = 62, 53%). Histologic subtype analysis was performed in 89 patients; of these, epithelial, sarcomatous and mixed types were identified in 46, 23 and 20 patients, respectively. An analysis of CT findings demonstrated that the involvement of mediastinal pleural (91%), interlobar fissure (87%) and lung parenchyma (48%) was significantly more frequent in sarcomatous type, as compared to epithelial (61% and p < 0.01; 35 and 4%, p < 0.0001, respectively) and mixed types (65% and p < 0.05; 10% and p < 0.0001; 10% and p < 0.01, respectively). Furthermore, there was a significant correlation between pericardial involvement and chest wall involvement (r = 0.42, p < 0.05) in sarcomatous type. Similarly, lymphadenopathy and parenchymal involvement (r = 0.23, p < 0.02), pericardial and chest wall involvement (r = 0.25, p < 0.01), chest wall and interlobar fissural involvement (r = 0.25, p < 0.01) were significantly correlated, when CT findings of all histologic subtypes were combined.

CONCLUSIONS

These results suggest that although CT findings of MPM vary, they may provide valuable clues to the diagnosis, at least in patients with a history of asbestos exposure. In addition, the presence of extensive lesions may suggest MPM of sarcomatous subtype.