Keywords:
Occupational / Environmental hazards, Education, Digital radiography, CT-High Resolution, Conventional radiography, Thorax, Respiratory system, Lung
Authors:
D. J. Martin, K. J. Litton, H. Adams; Cardiff/UK
DOI:
10.1594/esti2014/P-0108
Imaging findings OR Procedure details
Classic plaque appearances
- If calcified (only 10-15%) they are well defined,
often bilateral with an irregular outline (can resemble a holly leaf when seen en face): Fig. 1
- Non-calcified plaques are more difficult to identify on plain films but are most readily identified if they lie on the lateral chest wall
- CT readily identifies both calcified and non-calcified plaques: Fig. 2,
Fig. 3
Classic plaque distribution
- Postero-lateral chest wall between the seventh and tenth ribs
- Lateral chest wall between the sixth and ninth ribs
- Dome of the diaphragm: Fig. 2
- Mediastinal pleura: Fig. 4
- Typically absent from costophrenic angles and apices: Fig. 5
Atypical appearances
Visceral pleural plaques
- can arise in fissures: Fig. 6
- often associated with underlying parenchymal distortion (hairy plaques): Fig. 7
Examples to highlight the differences between plaques,
diffuse pleural thickening and mesothelioma
Diffuse pleural thickening: Fig. 8
- Forms following resolution of benign asbestos-related pleural effusion - however,
can occur following other causes of exudative effusions
- A smooth continuous sheet of pleural thickening extending over at least one-quater of the chest wall
- Can often involve the costophrenic angles and apices,
- Rarely calcifies
Mesothelioma: Fig. 9
- Pleural thickening which becomes progressively more lobulated
- Loss of volume of the affected hemithorax
- Often an associated effusion
- Tumour spread into interlobar fissures and onto mediastinal surface
- Tumour can directly extend through chest wall and diaphragm
Mimics of pleural plaques
There are a number of conditions or normal anatomical structures which can mimic pleural plaques particularly on a chest x-ray.
Knowledge of these potential mimics helps to differentiate them from pleural plaques and directs correct further investigation usually with CT.
Normal anatomical structures
- Pleural fat: Fig. 10
- Rib fractures
- Companion shadows for ribs
- Intercostal veins on CT: Fig. 11
Pathological mimics
- Pleural based lesions: Fig. 12 - loculated effusion,
fibroma,
inflammatory mass Fig. 13 ,
pleural metastases