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Interstitial Lung Diseases

Lung Diseases Pneumoconioses Obstructive Restrictive (Interstitial) Non-neoplastic lung reactions to inhalation of mineral dusts p Resistance to airflow q Expansion of lung parenchyma Encountered in work place Partial/ complete obstruction q Total lung capacity Causative agents y (at any level from , large Also known as Organic/ inorganic bronchi to terminal, respiratory y y Diffuse interstitial lung disease Chemical fumes y V bronchioles) y I apours nfiltrative lung disease tiologic agents y Agent Disease

M Interstitium ineral dust Coal dust Anthracosis (CWP) Consists of Silica y Basement membrane (endothelial, epithelial cells) Asbestos y Collagen fibres Beryllium Mesothelioma y Elastic tissue Iron oxide y Proteoglycans Organic dust y F ibroblasts Moldy hay Farmers lung y M ast cells Bagasses Bagassosis y L ymphocytes (occasional) Bird droppings Bird-breeders lung Chemical fumes/ vapours M ajor Categories (Interstitial Lung Diseases) Nitrous oxide, sulphur dioxide , , ARDS Fibrosing Ammonia, insecticides y I diopathic y Nonspecific interstitial Pathogenesis () y Cryptogenic organizing pneumonia Development of pneumoconiosis depend on y Associated with collagen vascular disease y Amount of dust retained in airways/ lungs y Pneumoconiosis y Size, shape, buoyancy of particles y D rug reactions y Particle solubility, physiochemical reactivity y Radiation pneumonitis y Possible additional affects of irritants Granulomatous 1-5 micro meter (in diameter) particles y Most dangerous y Hypersensitivity pneumonitis Reach terminal small airways & alveoli (settle in their linings) Pulmonary eosinophilia Particle size Smoking related Smaller Larger y Desquamative interstitial pneumonia Cause acute lung injury Cause fibrosing collagenous y Respiratory -associated interstitial lung disease pneumoconiosis

Other y Pulmonary alveolar protenosis

Commonest Diseases (terms of frequency) Environmental diseases ʹ Pneumoconiosis Granulomatous disease ʹ Sarcoidosis Idiopathic pulmonary fibrosis Collagen vascular disease Smoking related disease Pulmonary alveolar proteinosis

Pneumoconioses Coal Workers Pneumoconiosis (CWP) Silicosis Asbestosis (Anthracosis) Caused by inhalation of silicon dioxide Caused by inhaling coal dust for prolonged periods Family of crystalline hydrated silicates that form fibers Most prevalent in the world Lead to Seen in Presents as y Asymptomatic anthracosis y Asbestos workers y Slowly progressive nodular y Simple coal workers pneumoconiosis y People exposed to air-borne asbestos fibres y Fibrosing pneumoconiosis (no pulmonary dysfunction) (people living in old buildings) Seen in y Complicated coal workers pneumoconiosis 2 Forms of Asbestos y Sand blasters (progressive massive fibrosis) Serpentine Amphibole y Stone cutters (lung function is compromised) Commoner p Pathogenic y Foundry workers y Aerodynamic properties Quartz ʹ crystalline form of silica (common) y Solubility p Risk for lung carcinoma (2X) Go deeper down in lungs (due to structure, penetrate epithelium, enter interstitium) Cause fibrogenic reaction Exposure associated with y Mesothelioma y Lung carcinoma Act as tumour initiator, tumour promoter Pathogenesis Pathogenesis Pathogenesis Inhalation Chronic inhalation of dust from p carbon coal Initial injury q (` 20 years) (bifurcation of small airways) Silica particles interact with tissue, macrophages q q q Alveolar macrophages engulf dust, release cytokines Macrophages ingest asbestos fibers L ung macrophages ingest silica Stimulate inflammation Activated to release chemical mediators (macrophage killed) Collect in lung interstitium q q I (around bronchioles, alveoli) nduce fibrosis of lung Silica causes activation, release of chemical mediators q (IL-1, TNF) (Coal macules) Generalized interstitial pulmonary inflammation q q Interstitial fibrosis When combined with other minerals, Coal nodules develop as collagen accumulates Morphology quartz has q fibrogenic effect Focal emphysema develops q Fibrosis (limited to areas adjacent to coal macules) q Distortion of lung architecture Airflow obstruction Functional impairment Morphology Morphology

Asbestosis Asbestos fiber (coated with iron, calcium) Ferruginous body (iron stain)

Silicosis Silicotic nodule in lung B undles of interlacing pink collagen Asbestosis M inimal inflammatory reaction Fibrous pleural plaque Tan-white pleural plaques

Coal Worker͛s Pneumoconiosis (CWP) Focal deposition of coal dust Pigment-laden macrophages y Coal macules (1-2mm diameter) y Coal nodules (larger)

Asbestosis Fibrous pleural plaque (dense layers of collagen)

Complicated Coal Worker͛s Pneumoconiosis Progressive massive fibrosis lesion Cavitation, distortion of bronchiole, blood vessels Asbestosis Necrosis of cavity Diffuse pulmonary interstitial fibrosis Coal dust Collagen deposition (spread throughout lung) Dust-containing macrophages

Sarcoidosis Idiopathic Pulmonary Fibrosis (Cryptogenic Fibrosing Alveolitis) Systemic disease of unknown cause Clinicopathologic syndrome ʹ definite radiological, pathologic, clinical features Characterized by non-caseating granulomas in tissues, organs Lung involvement, hilar lymphadenopathy (seen 90% of cases) Pathogenesis (Idiopathic Pulmonary Fibrosis) Women (p Prevalence)(rare in SEA countries) Cause is unknown Repeated cycles of acute lung injury (by unidentified agent) Etiopathogenesis (Sarcoidosis) Followed by wound healing (causing fibrosis of injured sites) Due to disordered immune regulation Lead to widespread fibrosis of lung tissue Genetically predisposed individuals Exposed to certain environmental agents Morphology (Idiopathic Pulmonary Fibrosis) Factors Gross Immunogenic Cobblestone on pleural surface (due to retractions of scars) y Cell mediated response of CD4+ helper T cells to unidentified antigens Fibrosis of lung parenchyma (lower lobe predominance) Genetic y Familial, racial clustering of cases y Associated with HLA-A1, HLA-B8 Environment y Associated with Mycobacterial, propionibacterium acnes, rickettsia spp.

Morphology (Sarcoidosis)

Sarcoidosis Idiopathic Pulmonary Fibrosis Patchy interstitial fibrosis (usually interstitial pneumonia) Sarcoidosis Areas of microscopic honeycombing (arrows)

Sarcoidosis Sarcoidosis Foreign body giant cell Schaumann bodies Asterioid body (stellate inclusions) Laminated concretions (composed of Ca2+, proteins)

Idiopathic Pulmonary Fibrosis Honeycomb lung Porous network of fibrous walled cysts (resemble ʹ beehive/ sponge) Abnormal airspaces (due to combination of) y Alveolar destruction y y Bronchiolectasis y Formation of fibrous septa (between widely separated airspaces) Abnormal cystic air spaces lined by bronchiolar, alveolar epithelium

Differences ʹ Bullous Panlobular Emphysema, Honeycomb Lung Bullous Panlobular Emphysema Honeycomb Lung q Tissue consistency p Tissue consistency (due to fibrosis of honeycomb lung)

Collagen Vascular Disease Pulmonary Alveolar Proteinosis Involvement of lungs from Rare disease y SLE Can be y Rheumatoid arthritis y Acquired y Scleroderma y Congenital y Mixed connective disease y Secondary Pulmonary involvement can be y Usual interstitial pneumonia Morphology (Pulmonary Alveolar Proteinosis) y Non specific interstitial pneumonia y Organizing pneumonia y Bronchiolitis

Morphology (Collagen Vascular Disease)

Pulmonary Alveolar Proteinosis Peculiar, homogenous granular precipitate within alveoli Focal to confluent consolidation reaction M inimal inflammatory reaction Lung involvement in SLE (Collagen Vascular Disease) Cholesterol cleft, foamy macrophages Prominent interstitial fibroblastic proliferation Alveolar type 2 pneumocyte hyperplasia (cause alveolar collapse)(large arrows) Intraalveolar macrophage collection (small arrows) Organizing stage of

Smoking Related Interstitial Lung Disease Desquamative Interstitial Pneumonia Respiratory Bronchiolitis ʹ (DIP) Associated Interstitial Lung Disease 4th - 5th decades of life 4th - 5th decade of life Men (common) Men (common) Smokers Smokers Non-progressive illness Characterised by Large collection of macrophages in Presence of pigmented intraluminal alveoli (mild fibrous thickening of macrophages within respiratory alveolar walls) bronchioles Morphology Morphology

DIP Mild thickening of alveolar septa Respiratory Bronchiolitis-Associated Extensive airspace filling by Interstitial Lung Disease macrophages Tobacco pigment in macrophages (a) Airspace macrophages Collagenous scarring Chronic interstitial inflammatory Mild bronchiolar fibrosis (b) infiltrate Chronic inflammation (c)