WBR1102

Author	PageAuthor::William J Gibson (Reviewed by Serge Korjian)
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pathology, MainCategory::Pathophysiology
Sub Category	SubCategory::Pulmonology
Prompt	[[Prompt::A 64-year-old man presents to his primary care physician for shortness of breath, non-productive cough, fever and 15-pound weight loss. The patient denies a history of smoking, but reports working for 20 years as a sandblaster for a large construction firm. Chest X-ray shows diffuse micronodular opacities, particularly in the upper lobes. Chest CT shows enlargement of the hilum with eggshell-like calcifications. Which of the following would mostly likely be observed on lung biopsy?]]
Answer A	AnswerA::Ferruginous bodies
Answer A Explanation	[[AnswerAExp::Ferruginous bodies are characteristic of asbestosis. Asbestosis is a chronic inflammatory and fibrotic medical condition affecting the parenchymal tissue of the lungs caused by the inhalation and retention of asbestos fibers. Asbestosis increases the risk of bronchogenic carcinoma and mesothelioma. While bronchogenic carcinoma is more common in asbestosis, mesothelioma is a more specific complication of asbestosis, as the rate in the unexposed population is extremely low.]]
Answer B	AnswerB::Silica in alveolar macrophages
Answer B Explanation	[[AnswerBExp::Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. Microscopically, silicosis is characterized by silica in alveolar macrophages.]]
Answer C	AnswerC::Carbon-laden macrophages
Answer C Explanation	AnswerCExp::Collections of carbon-laden macrophages can be observed in coal-worker’s pneumoconiosis.
Answer D	AnswerD::Noncaseating granulomas
Answer D Explanation	[[AnswerDExp::Sarcoidosis is characterized by noncaseating granulomas. The pulmonary dysfunction, hilar enlargement and calcification observed in this patient are all consistent with sarcoidosis. However, “eggshell calcification” is classic for silicosis and the patient’s past exposure to silica particles while working as a sandblaster makes silicosis a more appropriate answer.]]
Answer E	AnswerE::Sheets of small, primitive appearing cells
Answer E Explanation	[[AnswerEExp::Small cell carcinoma, also known as “Oat cell carcinoma” is characterized by small, primitive appearing cells with scant cytoplasm. While weight loss and pulmonary symptoms are consistent with lung cancer, the classic “eggshell calcification” and exposure to silica as a sandblaster make silicosis a more appropriate answer.]]
Right Answer	RightAnswer::B
Explanation	[[Explanation::Silicosis is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in the form of nodular lesions in the upper lobes of the lungs. When fine particles of silica dust are deposited in the lungs, macrophages that ingest the dust particles will set off an inflammation response by releasing tumor necrosis factors, interleukin-1, leukotriene B4 and other cytokines. In turn, these stimulate fibroblasts to proliferate and produce collagen around the silica particle, thus resulting in fibrosis and the formation of the nodular lesions. Radiographically, chronic simple silicosis reveals a profusion of small (<10 mm in diameter) opacities, typically rounded, and predominating in the upper lung zones. These opacities are often referred to as “eggshell calcifications”. Educational Objective: Silicosis is a pneumoconiosis associated with exposure to silica particles. It causes predominantly upper lobe disease and will classically demonstrate “eggshell calcification”. References: Leung, Chi Chiu, Ignatius Tak Sun Yu, and Weihong Chen. "Silicosis." The Lancet 379.9830 (2012): 2008-2018. First Aid 2015 page 612 First Aid 2014 page 606]]
Approved	Approved::Yes
Keyword	WBRKeyword::Silicosis, WBRKeyword::Lung, WBRKeyword::Chest, WBRKeyword::Chest X-ray, WBRKeyword::Pulmonary, WBRKeyword::Restrictive lung disease, WBRKeyword::Pneumoconiosis, WBRKeyword::Pulmonary fibrosis
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