Study Syllabus for Classification of Radiographs of Pneumoconioses
Clinical Overview
Major Occupational Lung Diseases
Granulomatous Diseases
Chronic Beryllium Disease
Chronic beryllium disease (CBD) is an immune-mediated granulomatous lung disease resembling sarcoidosis that is caused by exposure to the lightweight metal beryllium. Exposure can occur in a number of industries including aerospace, defense, metal machining, electronics manufacture and recycling, and dental alloy/appliance production. Diagnosis requires a history of beryllium exposure; a positive blood or bronchoalveolar lavage (BAL) beryllium lymphocyte proliferation test (BeLPT); and noncaseating granulomas and/or mononuclear cell infiltrates on lung biopsy. A patient is considered beryllium sensitized when they have a positive blood BeLPT but no abnormal lung pathology. When histopathology is unavailable, a CBD diagnosis can be made based on the exposure history, a positive BeLPT, and imaging that shows abnormalities consistent with CBD. In early CBD, pulmonary function abnormalities, if present, include mild airflow limitation and abnormal gas exchange at rest or with exercise. Diffusing capacity (DLCO) may be low, and arterial blood gas analysis with exercise may show gas exchange abnormalities. With more advanced disease, PFTs show airflow limitation, restriction or a mixed pattern.
In early disease, the chest radiograph may be normal or show hilar adenopathy or parenchymal abnormalities. Parenchymal abnormalities include nodules (Fig. 16), ground glass, linear or alveolar opacities. The parenchymal abnormalities may be diffuse or upper lobe predominant. HRCT is more sensitive than chest x-ray in diagnosing CBD, however, HRCT is normal in up to 25% of patients with biopsy-proven CBD [Newman et al. 1994].
HRCT findings of CBD include parenchymal nodules of varying size, thickened septal lines, ground glass opacities, cystic cavitation, bronchial wall thickening, and hilar/mediastinal adenopathy [Newman et al. 1994; Naccache et al. 2003].
The lack of effective treatment, the progressive nature of the disease with on-going exposure, and the severity of fixed obstruction often seen in affected workers underscore the need for early recognition and control of causal exposures.
Chest radiographs are generally normal in early disease stages, but may show hyperinflation. Characteristic findings on HRCT include segmental or lobular areas of hypo-attenuation (air trapping) associated with narrowing of pulmonary vessels (mosaic perfusion), usually accentuated on expiratory images (Fig. 13).