125 Asbestosis

Clinical Presentation

68-year-old man with cough and dyspnea recently retired after a 35-year career in the insulation manufacturing industry

Radiologic Findings

HRCT (modified lung window) (Figs. 125.1A, 125.1B) demonstrates peripheral lower lobe architectural distortion with subpleural dot-like opacities (Fig. 125.1A), subpleural lines (Figs. 125.1A, 125.1B), and parenchymal bands (Fig. 125.1A) and additional findings of fibrosis with irregular interlobular septal thickening, intralobular interstitial thickening, irregular interfaces, and traction bronchiectasis or bronchiolectasis (Figs. 125.1A, 125.1B).

Diagnosis

Asbestosis

Differential Diagnosis

• Idiopathic Pulmonary Fibrosis

• Connective Tissue Lung Disease (scleroderma, rheumatoid arthritis)

• Drug Toxicity

• Post-Irradiation Pneumonitis

Discussion

Background

Inhalation of asbestos fibers is associated with a variety of pleural and parenchymal lung diseases, including pleural effusion, pleural plaques, rounded atelectasis, mesothelioma, asbestosis, and an increased incidence of lung cancer (Table 125.1). Asbestos fibers are naturally occurring fibrous silicates that have been widely used in industry because of their heat-resistant properties. They are usually categorized as chrysotile (serpentine) or amphibole (needle-like) fibers. Chrysotile fibers are more easily cleared from the lung and less strongly associated with carcinogenesis than the amphibole fibers. Asbestos fibers may be found within alveoli and have been isolated from the pleura, omentum, and mesentery. Pulmonary parenchymal fibrosis initially occurs in and around the respiratory bronchioles, preferentially occurring in the lower lobes and adjacent to visceral pleura, where asbestos fibers are known to accumulate.

Fig. 125.1

Etiology

Most urban-dwelling individuals have been exposed to asbestos as a frequent component of ambient air. High levels of exposure are associated with some occupations: asbestos mining and processing, working with asbestos cement, shipbuilding, construction, manufacture of insulation, handling brake lining and friction products, and production of floor tiles. Asbestosis occurs almost exclusively in individuals exposed to high concentrations of asbestos mineral fibers, often occurring over the course of many years. Federal regulations established in the late 1970s led to a sharp decline in high exposures to asbestos.