5. Infiltrative - Radiologic term
• Chest radiograph - ground glass shadow
• Diffuse infiltration by nodules/lines
6.
7.
8. Clinical features
1. Dyspnoea
2. Tachypnoea
3. Cyanosis
4. No wheezing
9. Pneumoconiosis
• Lung disease caused by inhalation of dust
• Synonyms:
• Dust diseases
• Occupational lung diseases
• Dusts –Inert
Predispose to TB
Predispose to neoplasia
10. Factors determining - disease
1. Size / shape of particles
2. Solubility
3. Amount of dust retained in lungs
4. Effect of other irritants - ex Smoke
5. Host factors:
Clearance mechanism
Immune status
11. Size of dust
• Particles larger than 5µm may reach
– Terminal airway
– Ingestion by alveolar macrophage
• Smaller than 1µm may
– Reach alveoli
– Stimulate macrophage
– Result in fibrosis
12. In the nose, the hair at the external
nares filter out the larger particles,
trapping almost all particles larger than
5µm.
In the trachea and bronchi, 90% of the
particles larger than 3-5µm are caught.
Particles between 0.5 and 2µm reach
the alveolar ducts and alveoli.
13. Solubility and cytotoxicity
• Smaller particles:
– Pulmonary fluid
– Rapid toxic levels
– Cause acute lung injury
• Larger particles:
– Resist dissolution
– Persist in lung for years
– Evoke fibrosis ex silicosis
14. Physiochemical reactivity
• Quartz particles
• Direct injury to tissue and cell membrane
• Can trigger proinflammatory / profibrosing
reaction
15. Systemic response
• Particles reach LN by macrophages
• Initiate immune response / amplifies local
reaction
• Particles translocate to blood
• Evokes systemic inflammation.
16. Host tissue response
1. Fibrous nodules ex coal workers
pneumoconiosis, silicosis.
2. Interstitial fibrosis ex asbestosis.
3. Hypersensitivity ex.berylliosis.
19. One form of hypersensitivity pneumonitis is known as farmer's lung - the farmer
inhales thermophilic actinomycetes in moldy hay that set off the reaction
20. "silo filler's disease" which is an acute chemical pneumonitis due to toxic
gases released from fermenting silage into the atmosphere inside the silo
22. Complicated CWP [PMF]
• Confluence of fibrosing reaction in lung
that is a complication of any
pneumoconiosis
• Common in CWP
• Can also be seen in silicosis
23. Anthracosis
• Coal - Innocuous
• Common in urban dwellers/smokers
• Carbon pigment in lung, lymphatics, LN
• Autopsy: linear streaks and aggregates in
pul. lymphatics, LNs
24. Simple CWP
• Coal macule: 1 to 2 mm, carbon laden
macrophages
• Coal nodules: larger than macule, contain
delicate collagen fibres
• Upper lobes, upper zones of lower lobes
heavily involved
• Located adjacent to resp bronchioles-
initial dust deposition site-centrilobular
emphysema
25. Complicated CWP (PMF)
In a background of simple CWP
Over years
Intensely blackened scars
Larger than 2 cms
May be upto 10 cms
Multiple,bilateral,involve upper,post region
Micro: dense collagen, pigment,
necrotic centre,with local ischemia
26. Caplan syndrome
(Rheumatoid pneumoconiosis)
• Development of rheumatoid arthritis in
CWP, silicosis, asbestosis
• Gross; round, firm nodules with central
necrosis, cavitation or calcification
• Micro: central zone of dust laden fibrinoid
necrosis enclosed by palisading
fibroblasts and mononuclear cells
27. Clinical features
• Cough with jet black sputum
• Dyspnoea
• Pul-HT, cor pulmonale
• TB and RA are more common in miners
• Increased risk for Ca. stomach
• Bronchogenic .ca is rare
28. Figure 15-18 Progressive massive
fibrosis superimposed on coal
workers' pneumoconiosis. The large,
blackened scars are located
principally in the upper lobe. Note the
extensions of scars into surrounding
parenchyma and retraction of
adjacent pleura.
31. Silicosis
knife grinders lung
• Silica (silicon dioxide)
• Caused by inhalation of crystaline silica
• Presents after decades of exposure
• Slowly progressing nodular, fibrosing
pneumoconiosis
32. Acute silicosis
• Heavy exposure over months to few years
• Generalized accumulation of
lipoproteinaceous material within alveoli
• Morphologically identical to alveolar
proteinosis.
38. Silica – Physical forms
Crystalline forms Amorphous forms
• Quartz • Talc
• Crystobalite • Vermiculite
• Tridymite • Mica
• Are fibrogenic • Less fibrogenic
39. IARC pointed out that only crystalline form is actually carcinogenic
40. Pathogenesis - Silicosis
• Silica - macrophage ingestion - direct
toxic effect
• Silica particles - activation and release of
mediators by viable macrophages
• IL-1, TNF, fibronectin, lipidmediators,
oxygen derived free radicles, fibrogenic
cytokines
• Mixed with other minerals, quartz has less
fibrogenic effect. ex: hematite.
41. Gross pathology
• Silicotic lung studded with well
circumscribed hard, fibrotic nodules,1 to 5
mm in diameters
• Scattered throughout the lung
• Simultaneous deposition of coal dust with
calcification
• Pleura thickened, adherent to chest wall
• Similar nodules in LN, pleura
42. Gross pathology contd…,
• X ray nodular lesions - egg shell shadows
• Lesion – necrosis, cavitation
• Complicated by TB, rheumatoid
pneumoconiosis.
46. Microscopy of silicosis
• Nodular lesions- concentric layers of
hyalinised collagen surrounded by dense
capsule of more condensed collagen
• Polarising microscopy --- birefringent silica
particles.
47. Figure 15-19 Advanced silicosis seen on transection of lung. Scarring has
contracted the upper lobe into a small dark mass (arrow). Note the dense
pleural thickening.
Figure 15-20 Several coalescent collagenous silicotic nodules.
51. Bright white collections of polarizable crystals are seen here, but are diffuse and centered
around vascular spaces. This is the lung of a patient with a long history of intravenous drug use
52. Clinical features-silicosis
Asymptomatic- routine chest x ray
X ray- fine nodularity in upper zones
Pulm functions –normal/mildly affected.
Slow to kill but impaired pulm fn severely limits
activity.
Depresses CMI
Increased susceptibility to TB
Crystalline silica - occupational source of
carcinogen.