Asbestosis

The diagnosis of asbestosis may be made on the basis of a combination of restrictive lung disease on pulmonary function tests as well as a diffusion abnormality, the presence of crackles at auscultation, and an abnormal chest radiograph. Ground-glass haze over the lower portions of the lungs characterizes the early stage, then radiographic features of interstitial pulmonary fibrosis are predominantly distributed in the lung basis and in subpleural regions of the lungs. The opacities are reticular and reticulonodular. When the fibrotic changes are more severe, features include involvement of the upper lobes, progressive lung volume loss and honeycombing. These radiographic features are nonspecific and are comparable to those of idiopathic pulmonary fibrosis. However, pleural plaques, diffuse pleural thickening and pleural calcification are to be found in 80% of patients with asbestosis. CT scanning offers an alternative method of evaluating patients with asbestosis (Fig.1). It is more sensitive than radiographs for detecting pleural and lung changes. It is indicated in patients with equivocal chest radiographs, particularly those with pleural plaques that make interpretation of underlying parenchyma difficult, and patients with clinical evidence of disease in whom chest radiographs are interpreted as normal. The earlier high resolution computed tomography (HRCT) findings include small centrilobular nodules, then intralobular lines and reticulation within the peripheral part of the lung bases. Irregular interlobular septal thickening may also be present with further progression of fibrosis. Architectural distorsion lung parenchyma, traction bronchiectasis and eventually honeycombing are seen (Fig. 1a). Other findings such as curvilinear subpleural lines and parenchymal bands are common but nonspecific.

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