Computed tomography features of liparitosis: a pneumoconiosis due to amorphous silica

Our plain-English summary of Computed tomography features of liparitosis: a pneumoconiosis due to amorphous silica, by S. Mazziotti, M. Gaeta, C. Costa, et al (The European Respiratory Journal, 2004).

The study

• Authors: S. Mazziotti, M. Gaeta, C. Costa, G. Ascenti, L. Barbaro Martino, G. Spatari, N. Settineri, M. Barbaro
• Journal: The European Respiratory Journal
• Published: 2004;23(2):208-13
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The purpose of this study was to describe the radiological features of pleural, parenchymal and mediastinal damage due to occupational inhalation of pumice. In total, 31 workers were evaluated for annual follow-up. Spiral computed tomography (CT) was obtained in the three patients with evident parenchymal abnormalities at chest radiograph. High-resolution computed tomography (HRCT) was performed in the remaining 28 subjects with no radiographical evidence of pleuropulmonary damage or evidence of pleural plaques, in order to exclude parenchymal involvement. Pumice samples were analysed by radiograph diffraction and scanning electron microscopy. Spiral CT showed parahilar conglomerate masses containing fine reticular calcifications in three of 31 (9.7%) patients. HRCT showed several bilateral pleural plaques, without any parenchymal lesion in eight of 28 (28.6%) cases. Statistical analysis indicated correlation between CT findings and pulmonary function, as well as exposure to pumice. The analysis of pumice excluded the presence of asbestos. The findings from this study suggest that pleural plaque may be the only sign of disease in patients with a history of pumice inhalation. However, conglomerate parahilar masses are probably due to exposure to massive amounts of heated pumice, and seem to have different pathogenesis and histopathological characteristics to silicosis.

In plain English

This study described chest scan findings in 31 men who had worked with pumice, a dust made mainly of amorphous (non-crystalline) silica, on Lipari, Italy. It was not a study of asbestos: no worker reported asbestos exposure, and the pumice particles were never fibrous, which the authors said excluded asbestos. From 1999 to 2002, workers had chest X-rays, breathing tests and CT scans. On X-ray, 22 of 31 showed no changes, 6 showed pleural plaques and 3, who had worked at drying ovens, showed masses near the centre of the lungs. Detailed CT of the remaining 28 workers found pleural plaques in 8 of 28 (28.6%), with no visible lesions in the lung tissue itself. No asbestos bodies were found in biopsy samples from two workers, and the plaques did not grow over up to 3 years. Worse scan findings were correlated with poorer lung function and more years of exposure, but not with smoking. The authors concluded that liparitosis is a poorly known disease due to amorphous silica with unique CT findings. They noted few workers had biopsies.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Radiological study of a group of exposed workers seen for annual follow-up (clinical exam, spirometry, chest radiograph, CT). It also included laboratory analysis of pumice samples and a review of autopsy material from two earlier patients (1950 to 1955).
• Who was studied: 31 male workers occupationally exposed to pumice on the island of Lipari, Sicily, Italy, evaluated from June 1999 to September 2002; mean age about 61 years
• Exposure: Pumice powder (described as amorphous, non-fibrous silica) from quarry work, with a mean of about 25 years working in the quarry. Jobs were excavation, mills, sieves and transportation. The three workers with masses had worked with desiccation (drying) ovens and heated pumice. Workers reported no exposure to asbestos or other mineral dusts. Respirable dust averaged 6.8 mg per cubic metre in 1981 and 1.9 mg per cubic metre in 1997.
• Main results:
  • On chest radiograph, 22 of 31 workers (71%, group 1) had no changes, 6 of 31 (19.3%, group 2) had pleural plaques, and 3 of 31 (9.7%, group 3) had parahilar masses
  • HRCT in the 28 workers of groups 1 and 2 showed pleural plaques in 8 of 28 (28.6%), without any parenchymal lesion seen. This confirmed the 6 group 2 cases and found 2 cases in group 1 not seen on chest radiograph.
  • Biopsy material from two group 2 patients showed the plaques were fibrotic. No asbestos bodies were found in the biopsy specimens.
  • In all patients, pleural plaques did not grow on annual follow-up CT for up to 3 years
  • Spiral CT in the three group 3 patients showed parahilar conglomerate masses containing fine reticular calcifications. No eggshell calcification was seen, and no pulmonary nodules typical of silicosis from crystalline silica were seen.
  • Lung function differed significantly between the three groups. Years of exposure also differed (mean 15.0 in group 1, 31.2 in group 2, 31.3 in group 3), but cigarette smoking did not differ significantly. Mean FVC was 90.6% of predicted in group 1, 83.5% in group 2 and 64.0% in group 3.
  • CT findings were significantly correlated with lung function measures and with years of exposure to pumice. Smoking habits did not appear to correlate with CT findings (Spearman test).
  • X-ray diffraction of pumice samples pointed mainly to amorphous silica. Electron microscopy showed irregular, glass-like particles that were never fibrous, which the authors said excluded asbestos.
• The authors' conclusion: The authors believed liparitosis is a poorly known but paradigmatic disease due to amorphous silica with unique CT findings. They suggested that pleural plaque may be the only sign of disease after pumice inhalation. They also said that, when amorphous silica exposure is not reported, such pleural findings call for differential diagnosis with other conditions including malignant mesothelioma.
• Limitations the authors state:
  • Biopsy evaluation was lacking in many patients (only two accepted needle biopsy)
  • The lack of findings in group 1 workers employed after 1985 might reflect shorter exposure or follow-up rather than improved working conditions

Topics

Medical terms in this study, explained in our Lexicon: Pneumoconiosis, Chest X-Ray, High-Resolution CT (HRCT), Pleural Plaques, Scanning Electron Microscopy (SEM), Bilateral, Silicosis.

Related studies

• CT patterns of pleuro-pulmonary damage caused by inhalation of pumice as a model of pneumoconiosis from non-fibrous amorphous silicates — C. Costa, G. Ascenti, et al. (2016)
• Preliminary study of positron emission tomography/computed tomography and plasma osteopontin levels in patients with asbestos-related pleural disease — S. Kurata, M. Ishibashi, et al. (2010)
• Computed tomography features in malignant pleural mesothelioma and other commonly seen pleural diseases — M. Metintas, I. Ucgun, et al. (2002)
• The usefulness of computed tomography in detecting asbestos-related pleural abnormalities in people who had indeterminate chest radiographs: the Libby, MT, experience — O.I. Muravov, W.E. Kaye, et al. (2005)
• Computed tomography findings in 66 patients with malignant pleural mesothelioma due to environmental exposure to asbestos — F. Okten, D. Köksal, et al. (2006)
• Diagnostic Value of Computed Tomography Imaging Features in Malignant Pleural Mesothelioma — M. Fortin, E. Cabon, et al. (2020)

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