1. Mohammad Tohidi M.D. Professor of Internal Medicine Department of Pulmonary Medicine Ghaem Hospital MUMS Mashhad IRAN Mohammad Tohidi M.D. Professor of Internal Medicine Department of Pulmonary Medicine Ghaem Hospital MUMS Mashhad IRAN

2. Silicosis

3. Case Scenario(1) 57 year old retired non-smoker man referred with the cc of dry cough for 1year.In addition he has had mild ED but no other complaint. Past Hx & system review were negative.His VS,general PE & 57 year old retired non-smoker man referred with the cc of dry cough for 1year.In addition he has had mild ED but no other complaint. Past Hx & system review were negative.His VS,general PE & chest exam were normal.Chest X ray showed diffuse reticulonodular pattern There were no hilar enlargement & calcification. chest exam were normal.Chest X ray showed diffuse reticulonodular pattern There were no hilar enlargement & calcification.

4. Case Scenario(2) HRCT scan of the lung revealed small rounded opacities & thickening of alveolar septa HRCT scan of the lung revealed small rounded opacities & thickening of alveolar septa no ground glass pattern,hilar adenopathy no ground glass pattern,hilar adenopathy & pleural effusion.He had >30 years Hx of stone cutting & grinding.With this Hx & immaging studies, in the absence of another causes,diagnosis of simple silicosis was apparent. & pleural effusion.He had >30 years Hx of stone cutting & grinding.With this Hx & immaging studies, in the absence of another causes,diagnosis of simple silicosis was apparent.

9. DEFINITION Silicosis is a fibrotic lung disease attributable to the inhalation of crystalline silica, usually in the form of quartz and, less commonly, as cristobalite and tridymite Silicosis is a fibrotic lung disease attributable to the inhalation of crystalline silica, usually in the form of quartz and, less commonly, as cristobalite and tridymite Amorphous silica is relatively nontoxic Amorphous silica is relatively nontoxic

10. Introduction Silicosis (also known as Grinder's disease and Potter's rot) is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. Silicosis (also known as Grinder's disease and Potter's rot) is a form of occupational lung disease caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs.occupational lung diseaseinflammation lungsoccupational lung diseaseinflammation lungs

11. Where’s it come from? Crystalline forms of silica (Silicon Dioxide or SiO2) include quartz, cristobalite, and tridymite. Quartz is the most common type, and is a major component of rocks including granite, slate, and sandstone.

13. Silica Silica is the second most common mineral on earth. It is found in sand, many rocks such as granite, sandstone, flint and slate, and in some coal and metallic ores. Silica is the second most common mineral on earth. It is found in sand, many rocks such as granite, sandstone, flint and slate, and in some coal and metallic ores.

14. Silica The cutting, breaking, crushing, drilling, grinding, or abrasive blasting of these materials may produce fine silica dust. The cutting, breaking, crushing, drilling, grinding, or abrasive blasting of these materials may produce fine silica dust.

15. Silicosis – history This respiratory disease was first recognized in 1705 by Ramazzini who noticed sand-like substances in the lungs of stonecutters This respiratory disease was first recognized in 1705 by Ramazzini who noticed sand-like substances in the lungs of stonecuttersRamazzini

16. Silicosis – history Full description by Bernardino Ramazzini (1633-1714) in early 18 th century. “...when the bodies of such workers are dissected, they have been found to be stuffed with small stones. ” Diseases of Workers (De Morbis Artificum Diatriba, 1713). Full description by Bernardino Ramazzini (1633-1714) in early 18 th century. “...when the bodies of such workers are dissected, they have been found to be stuffed with small stones. ” Diseases of Workers (De Morbis Artificum Diatriba, 1713).

17. Silicosis – history The name silicosis (from the Latin silex or flint) was attributed to Visconti in 1870 The name silicosis (from the Latin silex or flint) was attributed to Visconti in 1870

18. Silicosis - history First U.S. description in 19 th century. First U.S. description in 19 th century. Term silicosis introduced in 1870, from Latin silex, or flint. Term silicosis introduced in 1870, from Latin silex, or flint. Prevalence increased markedly with introduction of mechanized mining. Prevalence increased markedly with introduction of mechanized mining. Came to national attention 1930-1931 with construction of Hawk ’ s Nest Tunnel in Gauley Bridge, West Virginia. Called “ the worst industrial accident in U.S. history. ” At least 764 tunnel workers died from silicosis. Hawk ’ s Nest disaster led to Congressional hearings in 1936, and new laws protecting workers in many states. Came to national attention 1930-1931 with construction of Hawk ’ s Nest Tunnel in Gauley Bridge, West Virginia. Called “ the worst industrial accident in U.S. history. ” At least 764 tunnel workers died from silicosis. Hawk ’ s Nest disaster led to Congressional hearings in 1936, and new laws protecting workers in many states. Prevalence of silicosis has greatly declined in recent decades because of effective industrial hygiene measures. Prevalence of silicosis has greatly declined in recent decades because of effective industrial hygiene measures.

19. Silicosis - history The full name for this disease when caused by the specific exposure to fine silica dust found in volcanoes is pneumonoultramicroscopicsili covolcanoconiosis, and at 45 letters it is the longest word in any of the major English dictionaries. The full name for this disease when caused by the specific exposure to fine silica dust found in volcanoes is pneumonoultramicroscopicsili covolcanoconiosis, and at 45 letters it is the longest word in any of the major English dictionaries. pneumonoultramicroscopicsili covolcanoconiosis pneumonoultramicroscopicsili covolcanoconiosis

20. Silicosis - history The prevalence of silicosis led some men to grow what is called a miner's mustache, in an attempt to intercept as much dust as possible. The prevalence of silicosis led some men to grow what is called a miner's mustache, in an attempt to intercept as much dust as possible.

21. Diseases Associated with Exposure to Silica Dust(1) Silicosis Chronic silicosis Accelerated silicosis Acute silicosis (silicoproteinosis)(fine dust, intense exposure, high silica) Silicosis Chronic silicosis Accelerated silicosis Acute silicosis (silicoproteinosis)(fine dust, intense exposure, high silica) Progressive massive fibrosis Progressive massive fibrosis Chronic Obstructive Pulmonary Disease Emphysema Chronic bronchitis Mineral dust-induced small airway disease Chronic Obstructive Pulmonary Disease Emphysema Chronic bronchitis Mineral dust-induced small airway disease

22. Diseases Associated with Exposure to Silica Dust(2) Lung Cancer Mycobacterial Infection Mycobacterium tuberculosis Nontuberculous Mycobacteria Immune-Related Diseases Progressive systemic sclerosis Rheumatoid arthritis Chronic renal disease Systemic lupus erythematosus Lung Cancer Mycobacterial Infection Mycobacterium tuberculosis Nontuberculous Mycobacteria Immune-Related Diseases Progressive systemic sclerosis Rheumatoid arthritis Chronic renal disease Systemic lupus erythematosus

23. Pulmonary Toxicology Particle size is critical. Particle size is critical. Peak dust inhalation Peak dust inhalation occurs with particles occurs with particles having a diameter of 0.5 to having a diameter of 0.5 to 3 microns (μm). 3 microns (μm). RCS is invisible to the RCS is invisible to the human eye. human eye. Pulmonary clearance Pulmonary clearance mechanisms: mechanisms: macrophages & the macrophages & the mucociliary escalator mucociliary escalator

24. The induction period between initial silica exposure and development of radiographically detectable nodular silicosis is usually 10 years. Shorter induction periods are associated with heavy exposures, and acute silicosis may develop within 6 months to 2 years following massive silica exposure. The induction period between initial silica exposure and development of radiographically detectable nodular silicosis is usually 10 years. Shorter induction periods are associated with heavy exposures, and acute silicosis may develop within 6 months to 2 years following massive silica exposure.

25. Silicosis is an occupational hazard to mining, sandblasting, quarry, ceramics and foundry workers, as well as grinders, stonecutters and those continually exposed to silica dust. Silicosis is an occupational hazard to mining, sandblasting, quarry, ceramics and foundry workers, as well as grinders, stonecutters and those continually exposed to silica dust.

26. Variety of occupations Construction, and surface and underground rock drilling Construction, and surface and underground rock drilling Foundries are also a main source of silica dust Foundries are also a main source of silica dust workers involved with the repair, rehabilitation, or demolition of concrete structures workers involved with the repair, rehabilitation, or demolition of concrete structures

27. Variety of occupations New types of pneumoconiosis often turn out to be silicosis in an industry not previously thought to be at risk or a mixed-dust pneumoconiosis in which silica is implicated with other dusts New types of pneumoconiosis often turn out to be silicosis in an industry not previously thought to be at risk or a mixed-dust pneumoconiosis in which silica is implicated with other dusts Silicosis is often the result of exposure in the remote past and not in the current workplace Silicosis is often the result of exposure in the remote past and not in the current workplace

28. Pathology(1) When small silica dust particles are inhaled, they can embed themselves deeply into the tiny alveolar sacs and ducts in the lungs, where oxygen and carbon dioxide gases are exchanged. There, the lungs cannot clear out the dust by mucous or coughing When small silica dust particles are inhaled, they can embed themselves deeply into the tiny alveolar sacs and ducts in the lungs, where oxygen and carbon dioxide gases are exchanged. There, the lungs cannot clear out the dust by mucous or coughing

29. Pathology(2) Characteristic lung tissue pathology in nodular silicosis consists of fibrotic nodules with concentric "onion-skinned" arrangement of collagen fibers, central hyalinization, and a cellular peripheral zone, with lightly birefringent particles seen under polarized light Characteristic lung tissue pathology in nodular silicosis consists of fibrotic nodules with concentric "onion-skinned" arrangement of collagen fibers, central hyalinization, and a cellular peripheral zone, with lightly birefringent particles seen under polarized lightcollagen

31. Pathology(3) In acute silicosis, microscopic pathology shows a periodic acid-Schiff positive alveolar exudate (alveolar lipoproteinosis) and a cellular infiltrate of the alveolar walls In acute silicosis, microscopic pathology shows a periodic acid-Schiff positive alveolar exudate (alveolar lipoproteinosis) and a cellular infiltrate of the alveolar walls

32. Silicosis

33. PATHOGENESIS(1) 1. There is agreement that freshly fractured silica, such as that generated during sandblasting, is more toxic to the alveolar macrophages than is "aged" silica 2. clay components, may adhere to the surfaces of silica particles, producing "coated" silica, which is less toxic than uncoated silica dust 3. the incidence of silicosis is decreased by concomitant exposure to other dusts

34. PATHOGENESIS(2) 4 The intensity of the exposure determines the nature of the lung injury. Low-intensity exposure generally produces aggregates of fibrosis with relative sparing of the lung architecture, whereas high- intensity exposure causes widespread pulmonary inflammation and collagen deposition 5 Individual susceptibility to the disease may play a role 5 Individual susceptibility to the disease may play a role

35. Particles engulfed by macrophages: Particles engulfed by macrophages: transported upward and removed from lungs retained in the lung “ Frustrated Phagocytosis ” transported upward and removed from lungs retained in the lung “ Frustrated Phagocytosis ” cascade of toxic effects cascade of toxic effects inflammatory process inflammatory process pneumoconiosis pneumoconiosis fibrosis in the lung tissue fibrosis in the lung tissue

36. Pathogenesis(3) 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 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 lesionsmacrophages inflammationinterleukin-1leukotriene B4cytokinesfibroblastsfibrosismacrophages inflammationinterleukin-1leukotriene B4cytokinesfibroblastsfibrosis

37. Pathogenesis(4) Furthermore, the surface of silicon dust can generate silicon-based radicals that lead to the production of hydroxyl and oxygen radicals, as well as hydrogen peroxide, which can inflict damage to the surrounding cells Furthermore, the surface of silicon dust can generate silicon-based radicals that lead to the production of hydroxyl and oxygen radicals, as well as hydrogen peroxide, which can inflict damage to the surrounding cells hydroxylhydrogen peroxide hydroxylhydrogen peroxide

38. Silicosis Silicosis MC chronic occupational disease in the world MC chronic occupational disease in the world caused by inhalation of crystalline silicon dioxide (silica). caused by inhalation of crystalline silicon dioxide (silica). Acute silicosis -accumulation of a lipoproteinaceous material within alveoli Acute silicosis -accumulation of a lipoproteinaceous material within alveoli Chronic silicosis - slowly progressing, nodular, Fibrosing pneumoconiosis Chronic silicosis - slowly progressing, nodular, Fibrosing pneumoconiosis Pathogenesis Pathogenesis crystalline forms -more fibrogenic (quartz – worst) crystalline forms -more fibrogenic (quartz – worst) silica particles  lung macrophages ingest them  activation and release of mediators  IL-1, TNF, oxygen-derived free radicals silica particles  lung macrophages ingest them  activation and release of mediators  IL-1, TNF, oxygen-derived free radicals Anti-TNF monoclonal antibodies can block lung collagen accumulation in mice Anti-TNF monoclonal antibodies can block lung collagen accumulation in mice Morphology. Morphology. Early stages – tiny nodules in the upper zonesEarly stages – tiny nodules in the upper zones disease progresses – nodules coalesce into hard, collagenous scars  central softening and cavitation (due to superimposed tuberculosis or to ischemia)disease progresses – nodules coalesce into hard, collagenous scars  central softening and cavitation (due to superimposed tuberculosis or to ischemia) X-ray – egg shell calcification in the lymph nodesX-ray – egg shell calcification in the lymph nodes Advanced stage - PMFAdvanced stage - PMF Histology Histology Nodular lesions -concentric layers of hyalinized collagen surrounded by a dense capsule Nodular lesions -concentric layers of hyalinized collagen surrounded by a dense capsule Birefringent silica particles in polarized microscopy Birefringent silica particles in polarized microscopy

39. EPIDEMIOLOGY The prevalence of silicosis is difficult to estimate The prevalence of silicosis is difficult to estimate the reported cases have been estimated to represent only one third of the total cases of silicosis the reported cases have been estimated to represent only one third of the total cases of silicosis In calculating an individual's risk for silicosis, duration and intensity of exposure are of primary interest but peak exposure also may be important. In calculating an individual's risk for silicosis, duration and intensity of exposure are of primary interest but peak exposure also may be important.

40. EPIDEMIOLOGY(cont’d) In the United States, NIOSH has estimated that at least 1.7 million workers are exposed to silica, of whom between 1500 and 2360 will develop silicosis each year In the United States, NIOSH has estimated that at least 1.7 million workers are exposed to silica, of whom between 1500 and 2360 will develop silicosis each year

41. Prevalence Silicosis is the most common occupational lung disease worldwide, it occurs everywhere but is especially common in developing countries Silicosis is the most common occupational lung disease worldwide, it occurs everywhere but is especially common in developing countries

42. Silicosis deaths - declining www.cdc.gov/mmwr 1,157 (1968) 148 (2002) www.cdc.gov/mmwr

43. CLINICAL FEATURES(1) The main symptom is breathlessness, first noted during exertion and later at rest as the large working reserve of the lung is diminished. In chronic silicosis, in the absence of other respiratory disease, even this symptom may be absent The main symptom is breathlessness, first noted during exertion and later at rest as the large working reserve of the lung is diminished. In chronic silicosis, in the absence of other respiratory disease, even this symptom may be absent a patient with chronic silicosis may present without symptoms for assessment of an abnormal chest radiograph a patient with chronic silicosis may present without symptoms for assessment of an abnormal chest radiograph

44. CLINICAL FEATURES(2) The appearance of breathlessness may mark the development of a complication such as progressive massive fibrosis or tuberculosis, or may reflect associated airway disease The appearance of breathlessness may mark the development of a complication such as progressive massive fibrosis or tuberculosis, or may reflect associated airway disease Cough and sputum production are common symptoms and usually relate to chronic bronchitis, but may reflect the development of tuberculosis or lung cancer Cough and sputum production are common symptoms and usually relate to chronic bronchitis, but may reflect the development of tuberculosis or lung cancer

45. CLINICAL FEATURES(3) Chest pain is not a feature of silicosis, nor are systemic symptoms such as fever and weight loss, which should be attributed to tuberculosis or lung cancer until proven otherwise. Chest pain is not a feature of silicosis, nor are systemic symptoms such as fever and weight loss, which should be attributed to tuberculosis or lung cancer until proven otherwise. Clubbing is also not a feature of silicosis Clubbing is also not a feature of silicosis

46. CLINICAL FEATURES(4) In accelerated and acute silicosis, the time scale of symptom evolution is in years or months rather than decades. In acute silicosis, breathlessness may become disabling within months, followed by impaired gas exchange Cyanosis In accelerated and acute silicosis, the time scale of symptom evolution is in years or months rather than decades. In acute silicosis, breathlessness may become disabling within months, followed by impaired gas exchange Cyanosis Cyanosis Cor pulmonale Cor pulmonaleCor pulmonaleCor pulmonale Respiratory insufficiency Respiratory insufficiency

47. Patients with silicosis are particularly susceptible to tuberculosis (TB) infection - known as silicotuberculosis. The reason for the increased risk - 10-30 fold increased incidence - is not well understood. It is thought that silica damages pulmonary macrophages, inhibiting their ability to kill mycobacteria Patients with silicosis are particularly susceptible to tuberculosis (TB) infection - known as silicotuberculosis. The reason for the increased risk - 10-30 fold increased incidence - is not well understood. It is thought that silica damages pulmonary macrophages, inhibiting their ability to kill mycobacteriatuberculosismacrophagestuberculosismacrophages

48. Types of Silicosis (1) Chronic silicosis Occurs after 15-20 years of exposure to moderate to low levels of silica dust. Chronic silicosis itself is further subdivided into: simple simple complicated silicosis(PMF) complicated silicosis(PMF)

49. Chronic silicosis This is the most common type of silicosis. Patients with this type of silicosis may not have obvious symptoms, so a chest X-ray is necessary to determine if there is lung damage. This is the most common type of silicosis. Patients with this type of silicosis may not have obvious symptoms, so a chest X-ray is necessary to determine if there is lung damage.

50. (2) Asymptomatic silicosis Early cases of the disease do not present any symptoms

51. (3) Accelerated silicosis Silicosis that develops 5-10 years after high exposure to silica dust. Symptoms include severe shortness of breath, weakness, and weight loss Silicosis that develops 5-10 years after high exposure to silica dust. Symptoms include severe shortness of breath, weakness, and weight loss

52. (4) Acute silicosis Silicosis that develops a few months to 2 years after exposure to very high concentrations of silica dust. Silicosis that develops a few months to 2 years after exposure to very high concentrations of silica dust.

53. Diagnosis of Silicosis In general, three key elements play a role in the diagnosis of silicosis: In general, three key elements play a role in the diagnosis of silicosis: A history of silica exposure sufficient to cause the degree of illness and the appropriate latency from the time of first exposure A history of silica exposure sufficient to cause the degree of illness and the appropriate latency from the time of first exposure Chest imaging (usually a conventional chest radiograph) that shows opacities consistent with silicosis Chest imaging (usually a conventional chest radiograph) that shows opacities consistent with silicosis Absence of another diagnosis more likely to be responsible for the observed abnormalities Absence of another diagnosis more likely to be responsible for the observed abnormalities

54. Diagnosis of Silicosis Abnormal chest X-ray (or chest CT scan) consistent with silicosis Abnormal chest X-ray (or chest CT scan) consistent with silicosis History of significant exposure to silica dust History of significant exposure to silica dust Medical evaluation to exclude other possible causes of abnormal chest x-ray Medical evaluation to exclude other possible causes of abnormal chest x-ray Pulmonary function tests are helpful to gauge severity of impairment, but NOT for diagnosis. Pulmonary function tests are helpful to gauge severity of impairment, but NOT for diagnosis. Lung biopsy rarely indicated (since no effective treatment, biopsy is done only when other diagnoses are being considered) Lung biopsy rarely indicated (since no effective treatment, biopsy is done only when other diagnoses are being considered)

55. Silicosis can be misdiagnosed Silicosis can mimic: Silicosis can mimic: Sarcoidosis (benign inflammation of unknown cause)Sarcoidosis (benign inflammation of unknown cause) Idiopathic pulmonary fibrosis (lung scarring of unknown cause)Idiopathic pulmonary fibrosis (lung scarring of unknown cause) Lung cancerLung cancer Several other lung conditions (chronic infection, collagen-vascular disease, etc.)Several other lung conditions (chronic infection, collagen-vascular disease, etc.) Can usually make right diagnosis with detailed history (occupational & medical) or, rarely, a lung biopsy.

56. LUNG FUNCTION The lung function profile is determined by the extent of silicosis as well as associated or concomitant airway and vascular changes The lung function profile is determined by the extent of silicosis as well as associated or concomitant airway and vascular changes In chronic silicosis, spirometric tests (FEV1, FEV1/FVC, and maximal midexpiratory flow) usually reflect airflow limitation. In chronic silicosis, spirometric tests (FEV1, FEV1/FVC, and maximal midexpiratory flow) usually reflect airflow limitation.

57. LUNG FUNCTION In the accelerated and acute forms, functional changes are more marked and progression is more rapid. In acute silicosis, lung function shows a restrictive defect and impairment of gas exchange, which leads to respiratory failure and eventually to death from intractable hypoxemia In the accelerated and acute forms, functional changes are more marked and progression is more rapid. In acute silicosis, lung function shows a restrictive defect and impairment of gas exchange, which leads to respiratory failure and eventually to death from intractable hypoxemia

58. LUNG FUNCTION Reduction in diffusing capacity is generally apparent in more advanced chronic silicosis and probably reflects associated emphysema. Reduction in diffusing capacity is generally apparent in more advanced chronic silicosis and probably reflects associated emphysema. It is possible that most of the lung function changes associated with chronic silicosis can be attributed to the associated emphysema. It is possible that most of the lung function changes associated with chronic silicosis can be attributed to the associated emphysema.

59. Chest imaging The three main radiographic presentations of silicosis are: The three main radiographic presentations of silicosis are: simple silicosis progressive massive fibrosis simple silicosis progressive massive fibrosis silicoproteinosis silicoproteinosis

60. Simple silicosis Simple silicosis Simple silicosis refers to a profusion of small (less than 10 mm in diameter) nodular opacities (nodules). The nodules are generally rounded but can be irregular, and are distributed predominantly in the upper lung zones Simple silicosis refers to a profusion of small (less than 10 mm in diameter) nodular opacities (nodules). The nodules are generally rounded but can be irregular, and are distributed predominantly in the upper lung zones

61. Progressive massive fibrosis Progressive massive fibrosis Progressive massive fibrosis (PMF, or conglomerate silicosis) occurs when these small opacities gradually enlarge and coalesce to form larger, upper- or mid-zone opacities more than 10 mm in diameter Progressive massive fibrosis (PMF, or conglomerate silicosis) occurs when these small opacities gradually enlarge and coalesce to form larger, upper- or mid-zone opacities more than 10 mm in diameter

62. PMF The hila are retracted upward in association with upper lobe fibrosis and lower lobe hyperinflation The hila are retracted upward in association with upper lobe fibrosis and lower lobe hyperinflation Hilar adenopathy with prominent calcification is often present. The opacities of PMF can be asymmetrical, and may mimic a neoplastic process. Cavitation may also be present in advanced disease, or in the setting of mycobacterial superinfection Hilar adenopathy with prominent calcification is often present. The opacities of PMF can be asymmetrical, and may mimic a neoplastic process. Cavitation may also be present in advanced disease, or in the setting of mycobacterial superinfection

63. Silicoproteinosis Silicoproteinosis occurs following overwhelming exposure to respirable crystalline silica over a short time, and is the radiographic hallmark of acute silicosis The chest radiograph demonstrates a characteristic basilar alveolar filling pattern, without rounded opacities or lymph node calcifications. Silicoproteinosis occurs following overwhelming exposure to respirable crystalline silica over a short time, and is the radiographic hallmark of acute silicosis The chest radiograph demonstrates a characteristic basilar alveolar filling pattern, without rounded opacities or lymph node calcifications.

64. HRCT There is general agreement that CT/HRCT is superior to conventional chest radiography for documentation of PMF lesions and emphysematous changes associated with silicosis There is general agreement that CT/HRCT is superior to conventional chest radiography for documentation of PMF lesions and emphysematous changes associated with silicosis

65. pleural effusions are unusual,but pleural thickening appears to be common, especially among patients with more severe disease. In a series of 110 patients with biopsy proven silicosis followed for a mean of 14 years, pleural effusions were noted in 12 patients (11 percent), but pleural thickening was present in 64 patients (58 percent) pleural effusions are unusual,but pleural thickening appears to be common, especially among patients with more severe disease. In a series of 110 patients with biopsy proven silicosis followed for a mean of 14 years, pleural effusions were noted in 12 patients (11 percent), but pleural thickening was present in 64 patients (58 percent)

66. Normal Simple silicosis Normal Simple silicosis noal chest x-raynoal chest x-ray

67. Accelerated Silicosis ( Progressive Massive Fibrosis) normal chest x-ray PMF

68. Accelerated Silicosis (PMF) chest x-ray CT scan

69. Eggshell calcification – almost exclusively silicosis

70. RADIOGRAPHIC FEATURES(2) Silicotic nodules are usually, although not invariably, symmetrically distributed and tend to occur first in the upper zones.later, although not invariably, other zones are involved. Occasionally the nodules are calcified, resembling microlithiasis Silicotic nodules are usually, although not invariably, symmetrically distributed and tend to occur first in the upper zones.later, although not invariably, other zones are involved. Occasionally the nodules are calcified, resembling microlithiasis

71. RADIOGRAPHIC FEATURES(3) Enlargement of the hilar nodes may precede the development of the parenchymal lesions. "Eggshell" calcification, when present, is strongly suggestive although not pathognomonic, of silicosis Enlargement of the hilar nodes may precede the development of the parenchymal lesions. "Eggshell" calcification, when present, is strongly suggestive although not pathognomonic, of silicosis Pleural plaques may occur but are not a common feature. Pleural plaques may occur but are not a common feature.

72. RADIOGRAPHIC FEATURES(4) Progressive massive fibrosis is characterized by the coalescence of small rounded opacities to form larger lesions they are graded on the ILO scale according to size and extent (categories A to C). Progressive massive fibrosis is characterized by the coalescence of small rounded opacities to form larger lesions they are graded on the ILO scale according to size and extent (categories A to C).

73. RADIOGRAPHIC FEATURES(5) CT assessment is superior to the chest radiograph not only in assessing the presence and extent of silicotic nodulation, but also in revealing early conglomeration. CT assessment is superior to the chest radiograph not only in assessing the presence and extent of silicotic nodulation, but also in revealing early conglomeration. With time, the mass lesions tend to contract, usually to the upper lobes, leaving hypertranslucent zones at their margins and often at the lung bases. In this process, small rounded opacities, previously evident, may disappear, resulting in a picture that needs to be distinguished from tuberculosis With time, the mass lesions tend to contract, usually to the upper lobes, leaving hypertranslucent zones at their margins and often at the lung bases. In this process, small rounded opacities, previously evident, may disappear, resulting in a picture that needs to be distinguished from tuberculosis

74. RADIOGRAPHIC FEATURES(6) The rapid development of several large lesions suggests rheumatoid silicosis, but new lesions, especially if cavitated, should be regarded as evidence of mycobacterial disease The rapid development of several large lesions suggests rheumatoid silicosis, but new lesions, especially if cavitated, should be regarded as evidence of mycobacterial disease Acute silicosis is characterized radiologically by diffuse changes that usually display an air space and interstitial pattern rather than the usual nodularity Acute silicosis is characterized radiologically by diffuse changes that usually display an air space and interstitial pattern rather than the usual nodularity

75. Diagnosis: Serology Hypergammaglobulinemia Hypergammaglobulinemia RF RF ANF ANF S-ACE S-ACE Increased incidence of systemic sclerosis Increased incidence of systemic sclerosis described in SA gold miners

76. Treatment Silicosis is an irreversible condition with no cure. Treatment options currently focus on alleviating the symptoms and preventing complications Silicosis is an irreversible condition with no cure. Treatment options currently focus on alleviating the symptoms and preventing complications

77. Treatment The disease will generally progress even without further exposure,but the rate of deterioration is probably reduced The disease will generally progress even without further exposure,but the rate of deterioration is probably reduced

78. Treatment There is currently interest in the use of lung lavage to remove silica from the lung, but a favorable impact on progression of acute or chronic silicosis has not been demonstrated. There is currently interest in the use of lung lavage to remove silica from the lung, but a favorable impact on progression of acute or chronic silicosis has not been demonstrated.

79. Treatment Treatment of all forms of silicosis should be directed toward control of mycobacterial disease. This is especially true for acute and accelerated silicosis and silicosis in workers with human immunodeficiency virus infection Treatment of all forms of silicosis should be directed toward control of mycobacterial disease. This is especially true for acute and accelerated silicosis and silicosis in workers with human immunodeficiency virus infection All patients with silicosis should have a tuberculin skin test and, if it is positive, be offered treatment for latent tuberculosis infection All patients with silicosis should have a tuberculin skin test and, if it is positive, be offered treatment for latent tuberculosis infection

80. Treatment Interventions to interrupt the inflammatory process that leads to chronic silicosis including the inhalation of aluminum or polyvinylpyridine-N-oxide and oral tetrandine have not been shown to be successful Interventions to interrupt the inflammatory process that leads to chronic silicosis including the inhalation of aluminum or polyvinylpyridine-N-oxide and oral tetrandine have not been shown to be successful

81. Treatment The interaction between silica exposure and smoking in the development of COPD makes it particularly important to implement smoking cessation programs in the workplace The interaction between silica exposure and smoking in the development of COPD makes it particularly important to implement smoking cessation programs in the workplace

82. Treatment Because acute and accelerated silicosis carry such a poor prognosis and tend to occur in younger persons, consideration should be given to lung transplantation in such cases Because acute and accelerated silicosis carry such a poor prognosis and tend to occur in younger persons, consideration should be given to lung transplantation in such cases

83. Prevention The best way to prevent silicosis is to identify work- place activities that produce crystalline silica dust and then to eliminate or control the dust. Water spray is often used where dust emanates. Dust can also be controlled through dry air filtering The best way to prevent silicosis is to identify work- place activities that produce crystalline silica dust and then to eliminate or control the dust. Water spray is often used where dust emanates. Dust can also be controlled through dry air filtering

84. Prevention The most important aspect of the management of silicosis relates to its prevention The most important aspect of the management of silicosis relates to its prevention a sustained effort must be made to increase awareness of silicosis. Recent deaths from silicosis in younger individuals in the United States have occurred after exposure in the construction and manufacturing sectors, with none from mining a sustained effort must be made to increase awareness of silicosis. Recent deaths from silicosis in younger individuals in the United States have occurred after exposure in the construction and manufacturing sectors, with none from mining

85. Silicosis Silicosis MC chronic occupational disease in the world MC chronic occupational disease in the world caused by inhalation of crystalline silicon dioxide (silica). caused by inhalation of crystalline silicon dioxide (silica). Acute silicosis -accumulation of a lipoproteinaceous material within alveoli Acute silicosis -accumulation of a lipoproteinaceous material within alveoli Chronic silicosis - slowly progressing, nodular, Fibrosing pneumoconiosis Chronic silicosis - slowly progressing, nodular, Fibrosing pneumoconiosis Pathogenesis Pathogenesis crystalline forms -more fibrogenic (quartz – worst) crystalline forms -more fibrogenic (quartz – worst) silica particles  lung macrophages ingest them  activation and release of mediators  IL-1, TNF, oxygen-derived free radicals silica particles  lung macrophages ingest them  activation and release of mediators  IL-1, TNF, oxygen-derived free radicals Anti-TNF monoclonal antibodies can block lung collagen accumulation in mice Anti-TNF monoclonal antibodies can block lung collagen accumulation in mice Morphology. Morphology. Early stages – tiny nodules in the upper zonesEarly stages – tiny nodules in the upper zones disease progresses – nodules coalesce into hard, collagenous scars  central softening and cavitation (due to superimposed tuberculosis or to ischemia)disease progresses – nodules coalesce into hard, collagenous scars  central softening and cavitation (due to superimposed tuberculosis or to ischemia) X-ray – egg shell calcification in the lymph nodesX-ray – egg shell calcification in the lymph nodes Advanced stage - PMFAdvanced stage - PMF Histology Histology Nodular lesions -concentric layers of hyalinized collagen surrounded by a dense capsule Nodular lesions -concentric layers of hyalinized collagen surrounded by a dense capsule Birefringent silica particles in polarized microscopy Birefringent silica particles in polarized microscopy