Pathology of asbestos related diseases Asbestos exposure causes so many diseases ranging from asbestosis to Lung and Pleural cancer

2. ASBESTOS
• Family of crystalline hydrated silicates.
• Fibrous geometry.
• Occupational exposure to asbestos leads to:
 Parenchymal interstitial fibrosis (asbestosis)
 Localized fibrous plaques
 Pleural effusion
 Lung carcinomas
 Malignant pleural and peritoneal mesotheliomas
 Laryngeal carcinomas.

3. PATHOGENESIS
• Concentration, size, shape and solubility of different
forms.
• Two distinct forms :
 Serpentine: fiber is curly and flexible.
 Amphibole: fiber is straight , stiff and brittle.
• Serpentine chrysotile
 Most prevalent.
 Less pathogenic.
 More flexible, curled structure, likely to become impact in Upper Resp.
passage and removed by mucociliary elevator.

4. • Amphibole
 More pathogenic
 Less prevalent
 Related to structure, straight, stiff amphibole align themselves in
airstream and delivered deep to the lung
 Penetrate epithelial cells to reach interstitium
• Asbestos are fibrogenic
• Function as tumor initiator and promoter
• Oncogenic effects on mesothelium :
 Mediated by reactive free radicals
 Localized in the distal lung close to mesothelial layer

5. MORPHOLOGY
• Asbestosis
 Diffuse pulmonary interstitial fibrosis
 Presence of asbestos bodies
 Golden yellow, fusiform or beaded rods with translucent
center
 Consist of asbestos fibers coated with iron containing
proteinaceous material
 Formed with macrophages attempt to phagocytose
asbestos fibers

7.  Asbestosis begins in lower lobes and subpleuraly. The middle
and upper lobe of the lung get affected as the fibrosis
progresses
 Affected region become honeycombed.
 Fibrosis develops in visceral pleura
 Scarring trap and narrow pulmonary arteries and arterioles
causing pulmonary hypertension and cor pulmonale.

9. • Pleural plaques
 Most common manifestations of asbestos exposure
 Well circumscribed plaques of dense collage often containing
calcium
 Develops mostly on the anterior and posterolateral aspects of
parietal pleura and over domes of diaphragm
 Do not contain asbestos bodies
 Uncommonly asbestos exposure induce pleural effusion and
diffuse pleural fibrosis

11. CLINICAL FEATURES
• Findings are indistinguishable from other chronic interstitial
lung diseases
• Progressively worsening dyspnea appears 10 to 20 years after
exposure
• Accompanied by cough associated with productive sputum
• Disease remain static or progress to congestive heart failure,
cor pulmonale and death.

12. • Pleural plaques are asymptomatic and detected on
radiographs as circumscribed densities
• Lung carcinoma and malignant mesothelioma develop in
workers exposed to asbestos
• Concomitant cigarette smoking increases the risk of lung
carcinoma

14. SUMMARY
• Asbestos fiber 2 forms; stiff amphibole have greater fibrogenic and
carcinogenic potential than serpentine chrysotiles
• Asbestos exposure linked with 6 disease processes :
 Parenchymal interstitial fibrosis ( asbestosis )
 Localized fibrous plaques or, rarely, diffuse pleural fibrosis
 Pleural effusion
 Lung cancer
 Malignant pleural and peritoneal mesotheliomas
 Laryngeal cancer
• Cigarette smoking increases the risk of lung cancer in the setting of
asbestos exposure; even family members of workers exposed to asbestos
are at increased risk of cancer

15. THANK YOU