Interstitial Lung Disease

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Interstitial Lung Disease

• Prof. FA Carey

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Pulmonary interstitium

• Alveolar lining cells (types 1 and 2)
• Thin elastin-rich connective component containing
  capillary blood vessels

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Interstitial lung disease

• Early stage is alveolitis (injury with
  inflammatory cell infiltration)
• Late stage characterised by fibrosis
• Clinical effects due to hypoxia (respiratory
  failure) and cardiac failure

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Causes.

• Environmental (minerals, drugs, radiation.
  Post-ARDS)
• Hypersensitivity (mouldy hay, avian proteins)
• Unknown (idiopathic)
• Connective tissue diseases
• Fibrosing alveolitis
• Diagnosis based on clinical features often with
  biopsy

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Biopsy in interstitial lung disease

• Transbronchial biopsy special forceps used at
  bronchoscopy
• Thoracoscopic biopsy more invasive but more
  reliable and generates far more tissue

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Chronic Interstitial Disease

• Fibrosing alveolitis
• Sarcoidosis
• Extrinsic allergic alveolitis (hypersensitivity
  pneumonitis)
• Pneumoconiosis
• Connective tissue diseases

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Fibrosing Alveolitis

• aka cryptogenic fibrosing alveolitis (CFA), usual
  interstitial pneumonia (UIP)
• Progressive interstitial fibrosis of unknown
  cause
• Variable associated inflammation
• Finger clubbing

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Pathology

• Subpleural and basal fibrosis
• Inflammatory component variable
• Terminally lung structure replaced by dilated
  spaces surrounded by fibrous walls

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Fibrosing alveolitis (early)
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Fibrosing alveolitis (late honeycombing)
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Honeycombing basal/subpleural (a splint!)
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Extrinsic allergic alveolitis (hypersensitivity
pneumonitis)

• Chronic inflammatory disease
• Small airways
• Interstitium
• Occasional granulomas

• Allergic origin
• Type III hypersensitivity
• Type IV hypersensitivity

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EAA inflammatory interstitial expansion
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EAA - granuloma
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Causes of EAA

• Thermophilic bacteria Farmers lung
• Avian proteins Bird fanciers lung
• Fungi Malt workers lung
• Precipitins (antibodies) often detectable in
  serum. Unusual cases come to biopsy.

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Sarcoidosis

• Multisystem granulomatous disorder of unknown
  cause (defined by histological means)
• Pulmonary involvement is common
• Most cases mild and self-limiting

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Other manifestations of sarcoidosis

• Uveitis (inflammation of iris)
• Erythema nodosum
• Lymphadenopathy
• Hypercalcaemia

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Transbronchial biopsy - sarcoidosis
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Sarcoidosis - granuloma
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Apical scarring in sarcoidosis
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Sarcoid scarring and burnt-out granulomas
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Sarcoid - granulomas
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Pulmonary involvement in connective tissue
diseases

• Interstitial fibrosis (milder than fibrosing
  alveolitis)
• Pleural effusions
• Rheumatoid nodules

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Rheumatoid nodule
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Rheumatoid nodule
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Pneumoconiosis

• Lung disease caused by mineral dust exposure
• Asbestosis
• Coal workers lung
• Silicosis

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Thin whole mount section of a coal-workers lung
(unstained)
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Coal miner with progressive massive fibrosis
(unstained)
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Disease depends on.

• Particle size (1-5mm)
• Reactivity of particle
• Clearance of particle
• Host response

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Asbestos

• A silicate
• Serpentine (curved) asbestos fibres relatively
  safe
• Straight (amphibole) asbestos highly dangerous

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Asbestos

• Parietal pleural plaques
• Interstitial fibrosis (asbestosis)
• Bronchial carcinoma
• Mesothelioma

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Asbestosis bodies (from human lung)
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Association of asbestos bodies with fibrosis
(asbestosis)
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Pleural plaque on diaphragm