A 60-year-old man comes to the office for a work disability evaluation. Since high school, the patient has worked in a factory manufacturing granite and quartz countertops. His main concern is dyspnea that has slowly worsened over the last 2 years. The patient has rheumatoid arthritis, for which he was prescribed methotrexate 5 years ago; he stopped taking it "some time ago" because his symptoms did not improve. He owns an African Grey parrot and smoked heavily in his 30s and 40s. Physical examination is notable for coarse inspiratory crackles and squawks that are loudest in the upper lung fields. Bilateral digital clubbing and moderate metacarpophalangeal subluxation are present. Pulmonary function tests demonstrate moderately reduced total lung capacity. CT scan of the chest is shown in the image below: Which of the following factors best explains this patient's respiratory disease?

Question

A 60-year-old man comes to the office for a work disability evaluation.  Since high school, the patient has worked in a factory manufacturing granite and quartz countertops.  His main concern is dyspnea that has slowly worsened over the last 2 years.  The patient has rheumatoid arthritis, for which he was prescribed methotrexate 5 years ago; he stopped taking it "some time ago" because his symptoms did not improve.  He owns an African Grey parrot and smoked heavily in his 30s and 40s.  Physical examination is notable for coarse inspiratory crackles and squawks that are loudest in the upper lung fields.  Bilateral digital clubbing and moderate metacarpophalangeal subluxation are present.  Pulmonary function tests demonstrate moderately reduced total lung capacity.  CT scan of the chest is shown in the image below:  Which of the following factors best explains this patient's respiratory disease?

Quizplus · Accepted Answer

11ec25c8_d4c0_4555_bc81_ad51e2e0f9b3_MD0003_00 This patient with rheumatoid arthritis has chronic exposure to respirable silica crystals (stone countertop manufacturing). He has clubbing and auscultatory findings of pulmonary fibrosis (eg, crackles, squawks). CT scan of the chest reveals confluent areas of bilateral upper lobe fibrosis and densely calcified lymphadenopathy; pulmonary function tests reveal restriction (reduced total lung capacity). This presentation is highly suggestive of chronic silicosis. CT scan of the chest Chronic silicosis, an occupational interstitial lung disease, occurs when silica dust is inhaled by workers in high-risk professions (eg, stone cutting, abrasive blasting, quarry work). Upper lobe involvement reflects the inhalational pattern of exposure. Prolonged exposure overwhelms alveolar macrophage phagocytic capacity, triggering a maladaptive fibroinflammatory response. In the final stages, areas of scarring coalesce, termed progressive massive fibrosis (PMF). Over time, lymphatic injury leads to mediastinal and hilar node mineralization, sometimes appearing as eggshell calcifications (annular densities outlining the nodes). The association between silicosis and rheumatoid arthritis (eg, metacarpophalangeal subluxation) is well documented (Caplan syndrome, or rheumatoid pneumoconiosis), likely reflecting loss of immunologic tolerance due to persistent lung inflammation. The combination of occupational history and characteristic radiographic findings is sufficient to establish the diagnosis. Treatment is supportive and includes supplemental oxygen, smoking cessation, and alternative employment when possible; lung transplantation can be considered in patients with advanced PMF. (Choice A) Methotrexate can induce lung toxicity with fibrosis, manifesting with restriction and dyspnea. However, respiratory symptoms usually appear during active use and resolve, instead of progressing, on discontinuation; calcific adenopathy has never been reported. (Choice B) Cigarette smoking causes a spectrum of lung diseases. Carcinoma presents with a primary mass on imaging versus confluent bilateral fibrosis in PMF. Smoking-related interstitial lung disease (eg, desquamative interstitial pneumonia) occurs in active (vs former) smokers and presents with ground-glass infiltrates. (Choice D) Because it is an inhalational lung exposure, chronic hypersensitivity pneumonitis (bird fancier lung) can also present with bilateral upper lobe fibrosis. However, lymph node calcification is not seen. (Choice E) Although silicosis is associated with rheumatoid arthritis, lung involvement due to uncontrolled rheumatoid arthritis usually manifests with pulmonary fibrosis or pleural effusion. However, the characteristic pattern of pulmonary fibrosis is a usual interstitial pneumonia, characterized by lower lobe reticulation and peripheral honeycombing; calcific adenopathy is not seen. Educational objective: Chronic silicosis is a fibrotic occupational lung disease that occurs in high-risk workers (eg, stone cutters) exposed to respirable silica dust. It is caused by silica-induced, macrophage-driven inflammation and is characterized by upper lobe fibrosis and calcified hilar adenopathy. References: Silicosis and coal workers' pneumoconiosis. (http://www.ncbi.nlm.nih.gov/pubmed/10931786) Exposure to crystalline silica in abrasive blasting operations where silica and non-silica abrasives are used. (http://www.ncbi.nlm.nih.gov/pubmed/24353009) Silicosis: an update and guide for clinicians. (http://www.ncbi.nlm.nih.gov/pubmed/33153689)

A 60-Year-Old Man Comes to the Office for a Work