Pleural abnormalities and volume loss: Imaging considerations

Pleural thickening is a common finding on thoracic imaging studies, frequently representing the sequelae of pleural space infection or hemorrhage. Occasionally, pleural thickening may be due to neoplasia involving the pleural space, particularly adenocarcinoma and malignant pleural mesothelioma (MPM). MPM is a rare primary neoplasm arising from mesothelial cells lining serosal surfaces, typically the pleura. Asbestos exposure is a major risk factor for the development of MPM, and the neoplasm has a long latent period for development following asbestos exposure. MPM primarily affects men with an average age of 60 years at diagnosis. Chest radiographs in patients with MPM often show moderate or large pleural effusions or unilateral nodular pleural thickening, often with ipsilateral volume loss. Evidence of prior asbestos exposure is present in a minority of patients. Thoracic computed tomography shows findings suggesting pleural malignancy: pleural thickening that is nodular, greater than 1 cm, involves the mediastinum, and/or is circumferential. Magnetic resonance imaging may show the same findings and may have a relatively greater sensitivity for the detection of chest wall and diaphragm invasion. Positron emission tomographyimaging typically shows intense tracer activity within areas involved by MPM and may have an improved ability to detect extrathoracic spread of malignancy compared with cross sectional techniques. Most MPM patients are not surgical candidates at diagnosis, and treatment depends on multimodality therapy, including chemotherapy, radiation, and immunotherapy. While the prognosis remains poor, recent developments have shown improvements in survival and MPM diagnosis and treatment is an active area of research.