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Ostermayer: Created page with "Silicosis is an irreversible occupational lung disease caused by inhalation of respirable crystalline silica (silicon dioxide) dust, resulting in progressive nodular pulmonary fibrosis.Silicosis. ''StatPearls''. NCBI Bookshelf. Updated August 2023. It is the '''world's most prevalent occupational lung disease''' and has no cure. Once considered a disease of the past in developed countries, silicosis is experiencing a '..."

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Created page with "Silicosis is an irreversible occupational lung disease caused by inhalation of respirable crystalline silica (silicon dioxide) dust, resulting in progressive nodular pulmonary fibrosis.<ref name="StatPearls">Silicosis. ''StatPearls''. NCBI Bookshelf. Updated August 2023.</ref> It is the '''world's most prevalent occupational lung disease''' and has no cure.<ref name="StatPearls"/> Once considered a disease of the past in developed countries, silicosis is experiencing a '..."

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Silicosis is an irreversible occupational lung disease caused by inhalation of respirable crystalline silica (silicon dioxide) dust, resulting in progressive nodular pulmonary fibrosis.<ref name="StatPearls">Silicosis. ''StatPearls''. NCBI Bookshelf. Updated August 2023.</ref> It is the '''world's most prevalent occupational lung disease''' and has no cure.<ref name="StatPearls"/> Once considered a disease of the past in developed countries, silicosis is experiencing a '''resurgence driven by engineered stone (quartz) countertop fabrication''', which has created a new epidemic predominantly affecting young immigrant workers.<ref name="AJRCCM2025">Heinzerling A, et al. Deadly countertops: an urgent need to eliminate silicosis among engineered stone workers. ''Am J Respir Crit Care Med''. 2025.</ref> Silica is classified as a '''Group 1 human lung carcinogen''' by IARC.<ref name="Merck">Silicosis. ''Merck Manual Professional Edition''. Updated April 2025.</ref> The ED physician will encounter silicosis patients presenting with progressive dyspnea, respiratory infections (especially [[tuberculosis]]), [[pneumothorax]], and acute respiratory failure.

==Background==
*Crystalline silica (quartz) is one of the most abundant minerals on earth; occupational exposure occurs when silica-containing materials are cut, ground, drilled, or blasted, generating respirable dust (<10 µm)<ref name="StatPearls"/>
*'''High-risk occupations:''' Mining, quarrying, tunneling, sandblasting, construction (cutting/drilling concrete, brick, stone), foundry work, glass manufacturing, ceramics/pottery, gemstone cutting, dental laboratory work, stone countertop fabrication<ref name="StatPearls"/>
*'''The engineered stone epidemic:'''
**Engineered stone ("quartz") countertops contain '''>90% crystalline silica''' (vs. granite ~30–50%, marble <10%)<ref name="AJRCCM2025"/>
**US imports of engineered stone rose 800% from 2010 to 2018; now the most popular countertop material in the US<ref name="AJRCCM2025"/>
**By November 2024: 219 cases identified in California alone, including at least 14 deaths and 26 lung transplantations; median age 45; nearly all Latino immigrants<ref name="AJRCCM2025"/>
**Australia banned engineered stone effective July 2024 after 21% of screened workers were found to have silicosis<ref name="PMCReview">A review of silicosis and other silica-related diseases in the engineered stone countertop processing industry. ''J Occup Med Toxicol''. 2025.</ref>
**Many workers present with '''accelerated''' disease — severe fibrosis after only 5–15 years of exposure, far more aggressive than traditional chronic silicosis<ref name="JAMA2023">Fazio J, et al. Silicosis among immigrant engineered stone countertop fabrication workers in California. ''JAMA Intern Med''. 2023.</ref>
*'''Pathogenesis:''' Inhaled silica particles reach the terminal bronchioles and alveoli → engulfed by alveolar macrophages → macrophages cannot clear the particles → macrophage death releases silica and inflammatory mediators → cycle of chronic inflammation → fibroblast activation → '''irreversible nodular fibrosis'''<ref name="StatPearls"/>
*'''Three forms of silicosis:'''
**'''Chronic (classic) silicosis:''' Most common; latency '''10–30+ years''' after moderate exposure; may be simple (small nodules) or complicated (progressive massive fibrosis/PMF)
**'''Accelerated silicosis:''' Higher exposure; latency '''5–10 years'''; clinically and pathologically similar to chronic silicosis but progresses faster; this is the predominant form in engineered stone workers<ref name="JAMA2023"/>
**'''Acute silicosis (silicoproteinosis):''' Intense exposure over '''weeks to months'''; clinically resembles [[pulmonary alveolar proteinosis]]; rapidly progressive; often fatal<ref name="Merck"/>
*'''Associated conditions:'''
**'''[[Tuberculosis]]:''' Patients with silicosis have a '''~30-fold increased risk''' of TB (silicotuberculosis); even silica-exposed workers without silicosis have 3× the risk<ref name="Iowa">Silicosis. Iowa Health and Human Services. Updated August 2023.</ref>
**'''Lung cancer:''' Crystalline silica is IARC Group 1 carcinogen<ref name="Merck"/>
**'''Autoimmune diseases:''' Increased risk of [[rheumatoid arthritis]] (Caplan syndrome — silicosis + rheumatoid nodules), [[scleroderma]], [[SLE]], [[ANCA-associated vasculitis]]<ref name="StatPearls"/>
**'''Chronic renal disease'''<ref name="Iowa"/>
**'''COPD''' (emphysema, chronic bronchitis) — independent of smoking<ref name="Merck"/>
**Spontaneous [[pneumothorax]]<ref name="Iowa"/>
*OSHA PEL: 50 µg/m³ (8-hour TWA); updated in 2016<ref name="Merck"/>

==Clinical Features==
'''Chronic silicosis:'''
*Often '''asymptomatic''' for years — symptoms lag behind radiographic disease
*Progressive '''exertional dyspnea''' (most common symptom)
*Chronic dry cough (may become productive with superimposed infection)
*Fatigue, reduced exercise tolerance
*'''Physical exam:''' May be normal early; bibasal inspiratory crackles; advanced disease: signs of right heart failure ([[cor pulmonale]]), clubbing (uncommon unless complicated by other ILD or malignancy)
*'''Progressive massive fibrosis (PMF):''' Coalescence of nodules into large opacities (>1 cm); marked dyspnea, severe restriction, respiratory failure<ref name="StatPearls"/>

'''Accelerated silicosis (engineered stone):'''
*Younger patients (median ~45 years in US cases; some as young as late 20s)<ref name="JAMA2023"/>
*More rapid progression to PMF and respiratory failure
*Many present with '''advanced disease at diagnosis''' — nearly half in the California cohort<ref name="JAMA2023"/>

'''Acute silicosis (silicoproteinosis):'''
*Onset weeks to few years after intense exposure
*Rapidly progressive dyspnea, cough, weight loss, fatigue
*May present with '''acute respiratory failure'''
*Resembles [[pulmonary alveolar proteinosis]] clinically and radiographically (bilateral alveolar filling pattern)<ref name="Merck"/>
*Poor prognosis; often fatal<ref name="Merck"/>

'''ED presentations:'''
*Progressive dyspnea with occupational exposure history
*Superimposed respiratory infection ('''always consider TB''' — silicotuberculosis)
*Spontaneous [[pneumothorax]]
*Acute respiratory failure (acute silicosis or end-stage chronic disease)
*Hemoptysis (from PMF cavitation, TB, or broncholithiasis)
*Incidental finding of bilateral upper-lobe nodules on CT obtained for another reason

==Differential Diagnosis==
*[[Tuberculosis]] (may coexist with silicosis — silicotuberculosis; cavitary lesions in PMF raise concern for TB superinfection)
*[[Sarcoidosis]] (bilateral hilar lymphadenopathy + upper-lobe nodules; noncaseating granulomas; no occupational exposure)
*[[Beryllium toxicity|Chronic beryllium disease]] (requires BeLPT to distinguish; identical imaging possible)
*Other pneumoconioses: [[Asbestosis]] (basal-predominant fibrosis + pleural plaques), coal workers' pneumoconiosis (similar imaging but different exposure)
*[[Idiopathic pulmonary fibrosis]] (basal-predominant; UIP pattern; no occupational exposure)
*[[Hypersensitivity pneumonitis]] (exposure history differs; centrilobular nodules and air trapping)
*Pulmonary alveolar proteinosis (for acute silicosis — "crazy-paving" pattern)
*Metastatic disease or lymphoma (for PMF masses)
*Lung cancer (may coexist; silica is carcinogenic)
*Fungal infections ([[histoplasmosis]], [[coccidioidomycosis]])

==Evaluation==
===Workup===
'''History — critical:'''
*'''Detailed occupational history:''' All current and prior jobs; specifically ask about mining, construction, sandblasting, foundry, ceramics, glass, stone cutting/fabrication/installation, demolition, tunneling, dental lab work
*'''Ask specifically about stone countertop work''' — engineered stone/quartz/artificial stone fabrication, cutting, polishing, installation; many workers may not realize this is a silica-exposure occupation<ref name="AJRCCM2025"/>
*Duration of exposure, use of respiratory protection, wet vs. dry cutting methods
*Smoking history (compounds risk; assess for concomitant COPD)
*TB risk factors and prior testing
*Immigration status may affect healthcare access — provide resources regardless of documentation status

'''Laboratory (ED):'''
*CBC, CMP
*ABG/VBG: Hypoxemia; exercise desaturation in moderate disease
*Sputum for AFB smear, culture, and mycobacterial PCR if TB suspected (silicotuberculosis)
*'''Annual TB screening''' is recommended for all silica-exposed patients (tuberculin skin test or IGRA) — initiate if not recently done<ref name="Merck"/>
*No specific serum biomarker for silicosis
*Procalcitonin, blood cultures if concurrent infection suspected
*BNP/NT-proBNP if [[cor pulmonale]] or right heart failure suspected

'''Imaging:'''

''Chest X-ray:''
*'''Small round opacities''' in the upper and middle lung zones — the classic finding; graded by ILO classification (profusion and size: p, q, r)<ref name="StatPearls"/>
*'''Eggshell calcification''' of hilar lymph nodes — not pathognomonic but highly suggestive (~5–10% of cases)<ref name="Wikipedia">Silicosis. ''Wikipedia''. Updated March 2026.</ref>
*'''Progressive massive fibrosis (PMF):''' Large opacities (>1 cm), typically in upper lobes, often bilateral and symmetric; may cavitate (raises concern for TB, anaerobic infection, or necrosis)
*Hilar and mediastinal lymphadenopathy
*Compensatory emphysema peripheral to conglomerate nodules
*Acute silicosis: Bilateral alveolar/ground-glass pattern resembling pulmonary edema or alveolar proteinosis; Kerley B lines; pleural effusions may occur<ref name="CHEST2024">Managing silicosis in the United States. ''CHEST Pulmonary''. 2024.</ref>

''HRCT — more sensitive than CXR:''
*Small centrilobular and subpleural nodules, '''upper-zone predominant'''
*Nodule coalescence in PMF
*Associated emphysema
*Ground-glass opacities (acute or accelerated forms)
*Mediastinal/hilar lymphadenopathy (may show eggshell calcification)
*HRCT can detect silicosis when CXR is normal — CXR sensitivity for silicosis is only 35–48% compared to HRCT<ref name="PMCReview"/>

'''PFTs''' (outpatient):
*May be '''normal''' in simple chronic silicosis
*'''Restrictive''' pattern most common (reduced FVC, TLC)
*'''Obstructive''' pattern may be seen (especially with concurrent COPD/emphysema)
*'''Mixed''' restrictive-obstructive pattern in advanced disease
*Reduced DLCO<ref name="StatPearls"/>

===Diagnosis===
*'''Three elements:'''<ref name="Wikipedia"/>
**(1) History of sufficient occupational silica exposure
**(2) Chest imaging consistent with silicosis (CXR or HRCT)
**(3) Exclusion of other conditions that better explain the findings
*'''Tissue biopsy is generally NOT required''' — clinical-radiographic diagnosis is sufficient in most cases<ref name="StatPearls"/>
*Biopsy (transbronchial or surgical) if diagnosis is uncertain: '''concentric whorled collagenous nodules''' (silicotic nodules) with birefringent particles under polarized light<ref name="StatPearls"/>
*'''Always exclude TB''' — sputum AFB, cultures, +/- PCR in any patient with silicosis and new symptoms, cavitary lesions, or fever
*'''In the ED:''' Consider silicosis in any patient with bilateral upper-lobe nodularity or fibrosis + occupational exposure history; ensure appropriate referral even if the patient presents for an unrelated complaint

==Management==
'''There is no cure for silicosis — management is entirely supportive and preventive'''<ref name="Merck"/>

'''1. Remove from further silica exposure''' — the most important intervention; though disease may progress even after exposure ceases<ref name="ATS2014">Balmes JR, et al. ATS Statement. ''Am J Respir Crit Care Med''. 2014.</ref>

'''2. ED management:'''
*Supplemental O2 to maintain SpO2 ≥90%
*Bronchodilators (albuterol, ipratropium) — may benefit patients with obstructive component; ~25% have bronchodilator responsiveness<ref name="Merck"/>
*Non-invasive ventilation or intubation for respiratory failure
*Treat superimposed infection aggressively
*'''If TB suspected:''' Respiratory isolation, sputum AFB ×3, initiate empiric TB therapy if high clinical suspicion (silicotuberculosis has higher treatment failure and mortality than TB alone)<ref name="Merck"/>
*Chest tube for [[pneumothorax]]
*Treat cor pulmonale/right heart failure if present (diuretics, supplemental O2)

'''3. TB management in silicosis:'''
*'''Latent TB infection:''' Treatment is strongly recommended in all silicosis patients with positive TST or IGRA, regardless of age<ref name="Merck"/>
*'''Active TB:''' Standard anti-TB regimens; may require prolonged treatment courses due to higher treatment failure rates in silicotuberculosis<ref name="Iowa"/>
*Screen annually with TST or IGRA<ref name="Merck"/>

'''4. Acute silicosis (silicoproteinosis):'''
*'''Whole lung lavage''' has been used (similar to treatment for pulmonary alveolar proteinosis); clinical benefit not well established<ref name="Merck"/>
*Systemic corticosteroids — limited evidence; may provide modest benefit
*Prognosis is poor regardless of treatment

'''5. Long-term management (coordinate with pulmonology/occupational medicine):'''
*Smoking cessation (mandatory — compounds injury and cancer risk)
*Pulmonary rehabilitation
*Supplemental O2 for chronic hypoxemia
*Vaccinations: Annual [[influenza]], [[Pneumococcal vaccination|pneumococcal]], COVID-19
*Lung cancer screening (silica is Group 1 carcinogen)<ref name="Merck"/>
*'''Lung transplantation''' for end-stage disease (PMF with respiratory failure); increasing demand from engineered stone workers<ref name="AJRCCM2025"/>
*No proven antifibrotic therapy for silicosis (nintedanib and pirfenidone have not been specifically studied in silicosis)

'''6. Reporting:'''
*Silicosis is a '''reportable occupational disease''' in most jurisdictions — notify public health/occupational health authorities
*Document occupational exposure history thoroughly (may be needed for workers' compensation claims)

==Disposition==
*'''Admit:'''
**Acute respiratory failure
**Suspected silicotuberculosis (respiratory isolation pending AFB results)
**Acute silicosis with progressive hypoxemia
**Pneumothorax requiring chest tube
**Hemoptysis requiring evaluation (PMF cavitation, TB, malignancy)
**Severe exacerbation of known silicosis (infection, cor pulmonale)
*'''Discharge with close follow-up:'''
**Stable known silicosis with mild respiratory symptoms at baseline
**New suspected silicosis in stable patient — arrange:
***Pulmonology and/or occupational medicine referral within 1–2 weeks
***HRCT if not performed (CXR alone has low sensitivity)
***PFTs with DLCO
***TB screening (TST or IGRA) if not recently performed
**'''Discharge counseling:'''
***'''Avoid further silica exposure''' — discuss with employer; may require job change or engineering controls (wet cutting, ventilation, respirators)
***Return for worsening dyspnea, fever, hemoptysis, chest pain
***Smoking cessation
***Ensure vaccinations are current
***Report to occupational health for workplace evaluation and coworker screening
***'''For engineered stone workers:''' The LAM Foundation and occupational health resources may provide guidance; connect with legal resources if appropriate as this is an area of active litigation and compensation

==See Also==
*[[Asbestosis]]
*[[Beryllium toxicity]]
*[[Pneumoconiosis]]
*[[Tuberculosis]]
*[[Pulmonary alveolar proteinosis]]
*[[Sarcoidosis]]
*[[Hypersensitivity pneumonitis]]
*[[Heavy metal toxicity]]

==External Links==
*[https://www.ncbi.nlm.nih.gov/books/NBK594245/ Silicosis — StatPearls]
*[https://www.merckmanuals.com/professional/pulmonary-disorders/environmental-and-occupational-pulmonary-diseases/silicosis Silicosis — Merck Manual Professional]
*[https://www.osha.gov/silica Respirable Crystalline Silica — OSHA]
*[https://www.cdc.gov/niosh/topics/silica/ Silica — NIOSH/CDC]
*[https://www.atsjournals.org/doi/full/10.1164/rccm.202410-2008VP Deadly Countertops: Engineered Stone Workers (AJRCCM 2025)]
*[https://www.chestpulmonary.org/article/S2949-7892(24)00069-2/fulltext Managing Silicosis in the United States (CHEST Pulmonary 2024)]

==References==
<references/>

[[Category:Pulmonary]]
[[Category:Toxicology]]

Silicosis - Revision history

Danbot: Strip excess bold

Danbot: Moved intro into Background as bullets; removed excessive bold from bullet lead-ins; added Pulmonary fibrosis differential template; bold retained for critical items only