Pulmonology · Occupational Lung Diseases
The facts most likely to be tested
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Coal worker's pneumoconiosis presents with upper lobe nodular opacities and is associated with anthracotic pigment accumulation.
Silicosis is characterized by eggshell calcification of hilar lymph nodes and increases the risk of Mycobacterium tuberculosis infection.
Asbestosis typically involves the lower lobes and is associated with pleural plaques and ferruginous bodies on histology.
Caplan syndrome is the combination of rheumatoid arthritis and pneumoconiosis resulting in large intrapulmonary nodules.
Berylliosis mimics sarcoidosis with non-caseating granulomas and is common in workers in the aerospace or electronics industries.
Byssinosis is caused by cotton dust exposure and classically presents with symptoms that are worse on the first day of the work week.
Mesothelioma is a highly aggressive malignancy of the pleura that is strongly associated with asbestos exposure, even in the absence of asbestosis.
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A 62-year-old male presents with progressive dyspnea and a non-productive cough. He worked for 30 years as a shipbuilder and pipefitter. Physical examination reveals bibasilar end-inspiratory crackles and clubbing of the digits. A chest radiograph demonstrates linear interstitial opacities in the lower lung fields and calcified pleural plaques along the diaphragm. Pulmonary function testing shows a restrictive pattern with decreased diffusing capacity.
What is the most likely diagnosis?
Asbestosis
The patient's history of shipbuilding (asbestos exposure) combined with lower lobe interstitial fibrosis and pleural plaques is pathognomonic for asbestosis, which is tested in Bet 3.
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High yield triage
Etiology / Epidemiology
Chronic inhalation of mineral dusts (silica, asbestos, coal, beryllium) causing irreversible interstitial lung disease.
Clinical Manifestations
Progressive dyspnea on exertion and non-productive cough; Caplan syndrome (rheumatoid nodules + pneumoconiosis).
Diagnosis
High-resolution CT (HRCT) is the gold standard; PFTs show a restrictive pattern (decreased TLC/DLCO).
Treatment
Supportive care; smoking cessation and oxygen therapy are the only interventions that improve survival.
Prognosis
Increased risk of cor pulmonale and malignancy; prognosis depends on the specific dust exposure.
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Epidemiology & Etiology
Occupational exposure is the primary driver, specifically in mining, sandblasting, construction, and aerospace. Silica exposure is common in sandblasting/stone cutting, while asbestos is linked to shipbuilding/insulation. Beryllium exposure occurs in high-tech electronics manufacturing.
Pertinent Anatomy
Inhaled particles deposit in the distal alveoli and terminal bronchioles. The resulting inflammation leads to interstitial fibrosis, primarily affecting the upper lobes (silicosis/coal worker's) or lower lobes (asbestosis).
Pathophysiology
Inhaled particles trigger alveolar macrophage activation and release of inflammatory cytokines. This leads to chronic fibroblast proliferation and collagen deposition. The process is irreversible and results in decreased lung compliance and impaired gas exchange.
Clinical Manifestations
Patients present with insidious dyspnea and dry cough. Caplan syndrome involves rheumatoid arthritis with intrapulmonary nodules. Red flags include rapid weight loss or hemoptysis, suggesting bronchogenic carcinoma or tuberculosis superinfection.
Diagnosis
HRCT is the diagnostic modality of choice to visualize ground-glass opacities or honeycombing. PFTs demonstrate a restrictive pattern with a reduced DLCO. Lung biopsy is rarely required but shows characteristic birefringent particles in silicosis or ferruginous bodies in asbestosis.
Treatment
Management is primarily supportive, focusing on pulmonary rehabilitation and vaccination (pneumococcal/influenza). Smoking cessation is mandatory to reduce the synergistic risk of lung cancer. Corticosteroids are generally ineffective for fibrosis but may be used for acute beryllium hypersensitivity.
Prognosis
Patients are at high risk for cor pulmonale and respiratory failure. Silicosis significantly increases the risk of tuberculosis (silicotuberculosis). Regular chest X-ray surveillance is required for high-risk occupations.
Differential Diagnosis
Sarcoidosis: hilar adenopathy and non-caseating granulomas
Hypersensitivity pneumonitis: exposure to organic antigens/mold
Idiopathic pulmonary fibrosis: older age, no occupational history
Tuberculosis: fever, night sweats, apical cavitation
Chronic obstructive pulmonary disease: obstructive pattern on PFTs