الرحمن الله الرحمن بسم الله بسم الرحیمالرحیم

SilicosisSilicosisBy : F. MovasatianBy : F. Movasatian

IntroductionIntroduction::

Most common pneumoconiosis in Most common pneumoconiosis in world(occupational exposure to world(occupational exposure to crystalline silica)crystalline silica)

Silica (silicon dioxide)Silica (silicon dioxide) : : Free: Free:

11--Crystalline Crystalline (Quartz,Cristobalite,Tridymite) (Quartz,Cristobalite,Tridymite)

22--Amorphous(Diatomite)Amorphous(Diatomite) Combined(silicates): Combined(silicates):

Asbestos,Talk,Kaoline. Asbestos,Talk,Kaoline.

Workers at riskWorkers at risk: :

--Miners or tunnelersMiners or tunnelers

--MillersMillers

--Quarry workers & stone workersQuarry workers & stone workers

--Foundry workersFoundry workers

--SandblastersSandblasters

--Pottery workersPottery workers

--Glass makersGlass makers

HistoryHistory

Length of employmentLength of employment

Exp measurementsExp measurements

Effective respiratory protectionEffective respiratory protection

PathogenesisPathogenesis::

Particles <5 Particles <5 μμm deposit in alveoli.m deposit in alveoli.

Particles <1 Particles <1 μμm the most fibrogenic . m the most fibrogenic .

80% of silica dust cleared quickly80% of silica dust cleared quickly

Particles interact with alveolar MQ Particles interact with alveolar MQ Lung inflammation, fibrosis, Lung inflammation, fibrosis, silicotic nodules (histo. Hallmark)silicotic nodules (histo. Hallmark)

SilicosisSilicosis:: simple silicosissimple silicosis

complicated or conglomerate s.complicated or conglomerate s.

(progressive massive fibrosis)(progressive massive fibrosis)

accelerated silicosisaccelerated silicosis

acute silicosisacute silicosis

Simple SilicosisSimple Silicosis::

No chest symptoms, productive No chest symptoms, productive cough.cough.

P/E: coarse soundsP/E: coarse sounds CXR: Rounded opacities(1-10mm) CXR: Rounded opacities(1-10mm)

+hilar LAP with distinctive +hilar LAP with distinctive calcification (Eggshell calcification)calcification (Eggshell calcification)

pp (up to 1.5 mm) (up to 1.5 mm) qq (1.5-3 mm) (1.5-3 mm) rr (3-10 mm) (3-10 mm)

Cont. Simple SilicosisCont. Simple Silicosis

HRCT is not more sensitive than HRCT is not more sensitive than CXR in early detection .CXR in early detection .

PFT: No significant impairment.PFT: No significant impairment.

Progressive massive Progressive massive fibrosisfibrosis:: PMF is result of conglomeration of small PMF is result of conglomeration of small

rounded opacities.rounded opacities. Chronic productive cough / exertional Chronic productive cough / exertional

dyspnea to respiratory failure.dyspnea to respiratory failure. P/E: decrease lung sounds.P/E: decrease lung sounds. CXR: nodules >1cm in upper zone CXR: nodules >1cm in upper zone

+emphysema in lower zone +emphysema in lower zone AA (>10mm, <50mm) (>10mm, <50mm) BB (>A but no > right upper zone) (>A but no > right upper zone) C C (> right upper zone) (> right upper zone) Pulmonary impairmentPulmonary impairment

Cont. PMFCont. PMF

Progression of silicosis depends onProgression of silicosis depends on::

Duration of exp.Duration of exp. Concentration of silica Concentration of silica Amount of silicosis in CXR.Amount of silicosis in CXR. Mycobacterium infectionMycobacterium infection

Accelerated silicosisAccelerated silicosis::

Time from silica exp., to X-Ray & Time from silica exp., to X-Ray & PFT changes is much shorter.PFT changes is much shorter.

Rapid progression to progressiveRapid progression to progressive

massive fibrosis.massive fibrosis.

Acute silicosisAcute silicosis:: Short duration of exp. to very high Short duration of exp. to very high

concentration of (fine,freshly cut ) concentration of (fine,freshly cut ) silicasilica

Rapid onset of chest symp. (1-3 Rapid onset of chest symp. (1-3 yr)and respiratory failure yr)and respiratory failure Death(<2yr)Death(<2yr)

CXR: diffuse alveolar infiltration, air CXR: diffuse alveolar infiltration, air bronchogram, ground glass, bronchogram, ground glass, cavity(small rounded opacities cavity(small rounded opacities arenot seen) arenot seen)

Silica exp. & TBSilica exp. & TB Incidence of TB is greater in Incidence of TB is greater in

accelerated or acute Silicosisaccelerated or acute Silicosis Silica exp. in the absence of silicosis Silica exp. in the absence of silicosis

is risk factor for TBis risk factor for TB Silica exp. Risk for TB Silica exp. Risk for TB Radiographic changes in silicosis Radiographic changes in silicosis

frequency of TB frequency of TB Silica exp. & TB Death 4 yrs Silica exp. & TB Death 4 yrs

earlier than TB alone earlier than TB alone

Cont. TB & silicosisCont. TB & silicosis DX : rapid worsening of CXR, decline DX : rapid worsening of CXR, decline

in lung function suspicion for in lung function suspicion for TBTB

regular PPD skin test (yearly )regular PPD skin test (yearly )

PPD(+) without active TB ,indicated PPD(+) without active TB ,indicated at least 1 yr INH prophylaxis.at least 1 yr INH prophylaxis.

DiagnosisDiagnosis

11--History of silica expHistory of silica exp..

22--Chest radiography consist with Chest radiography consist with silicosissilicosis..

33--R/O other illness that mimic silicosisR/O other illness that mimic silicosis . .

HRCT & Lung biopsy (open) if …HRCT & Lung biopsy (open) if …

PreventionPrevention Product substitution of silica with less Product substitution of silica with less

toxic particlestoxic particles

Engineering control of dust Engineering control of dust concentration concentration

Appropriate use of respiratory Appropriate use of respiratory protective devicesprotective devices

Medical screening: Medical screening: questionnaire, CXR, spirometryquestionnaire, CXR, spirometry

WHO recommendationWHO recommendation:: CXR CXR : : At baseline, after 2-3 years of At baseline, after 2-3 years of

exposure,exposure, then every 2-5 years. then every 2-5 years.

Spirometry Spirometry + + questionnairequestionnaire : : At baseline, then annually or at At baseline, then annually or at

the same frequency as CXR.the same frequency as CXR.

ManagementManagement Diagnosis of silicosis Remove Diagnosis of silicosis Remove Regular CXR and PPD skin test Regular CXR and PPD skin test Steroid helpful in Acute S. or Steroid helpful in Acute S. or

autoimmune dis. (INH prophylaxis) autoimmune dis. (INH prophylaxis) Whole lung lavage for acute silicosis ?Whole lung lavage for acute silicosis ? Tetrandrine Tetrandrine Lung trasplantationLung trasplantation

Crystalline silica (quartz, Crystalline silica (quartz, cristobalite) is carcinogen (group 1 cristobalite) is carcinogen (group 1 IARC)IARC)

Silicosis is associated with Silicosis is associated with autoimmune dis. (RA, SLE, autoimmune dis. (RA, SLE, Scleroderma)Scleroderma)