Silicosis is a pneumoconiosis characterized by "eggshell" calcifications of hilar lymph nodes. This patient was exposed to silica shavings/powder in the air while construction of the avaries took place.
Silicosis is caused by inhalation of crystalline silica dust and is the most prevalent chronic occupational disease in the world. It often presents with shortness of breath, cough, fever, and cyanosis. Diagnosis is determined by three factors: exposure to sufficient silica to cause disease, chest x-ray demonstrating eggshell calcifications in the hilar lymph nodes, and no underlying illnesses that are more likely to cause the abnormality. Biopsy of the calcified lesions would show nodules of birefringent silica particles surrounded by collagen.
Beaucham et al. discuss silicosis within the work environment. Occupational illnesses due to inhaling respirable silica dust affects millions of workers worldwide. The National Institute for Occupational Safety and Health (NIOSH), along with the World Health Organization, International Labour Organization and various other agencies, are working together in an attempt to eliminate silicosis exposures throughout the Americas. They intend to do this by implementing task-based hazard data and potential exposure information at various worksites.
Thomas et al. review silicosis in the United States. Since 2000, silica has been a known human carcinogen. It can produce fibrosis of the lungs, which leads to an increased susceptibility to developing tuberculosis. Although silicosis is untreatable, it is a preventable disease. It is crucial for the environmental health and safety professionals to inform industry workers about safety and health hazards associated with silica dust inhalation.
Figure A depicts the characteristic "eggshell" calcifications of the hilar lymph nodes. Illustration A is an overview image describing silicosis.
Answer 1: Asbestosis is associated with calcified pleural plaques and ferruginous bodies.
Answer 2: Progressive massive fibrosis, also known as Coal miner's lung (or Black Lung Disease, colloquially), is associated with perilymphatic accumulations of coal-dust laden macrophages.
Answer 4: Berylliosis presents with characteristic non-caseating granulomas in lungs and hilar nodes.
Answer 5: Bird fancier's lung is a hypersensitivity pneumonitis that presents with granuloma formation and is caused by contact with bird droppings. You have to build the aviaries before filling them with birds!
Thomas CR, Kelley TR. A brief review of silicosis in the United States. Environ Health Insights. 2010 May 18;4:21-6.
PMID:20523881 (Link to Abstract)
Beaucham CC, Lentz TJ, Rice FL. Expanding control banding for workplace silica exposures throughout the Americas. Int J Occup Environ Health. 2012 Oct-Dec;18(4):344-7. doi: 10.1179/2049396712Y.0000000001.
PMID:23433296 (Link to Abstract)
USMLE World Step 1 QBank Question #668. Copyright © USMLEWorld, LLC 2012.