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Pathogenesis of IPF
- Repeat stimulus leading to inflammation to aberrant wound healing to fibrosis
- There are genetic factors, some promoting a TH1 TH2 imbalance
- Injuries can be particles, chemicals, gastric reflux, viruses
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Epidemiology of IPF
- Men more than women
- Usually over age 40
- Smoking, farming, silica, wood dust, metal dust
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Diagnosis of IPF
- Exclusion!
- History is most important
- CXR reticular (mostly base), surgical lung biopsy
- UIP pattern HRCT
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Symptoms of IPF
- Dry, non productive cough
- Chronic, worsening dyspnea
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Physical Exam of IPF
- Clubbing
- Velcro inspiratory crackles
- Absence of clues suggesting CT disease
- Restrictive
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UIP
- Lots of causes including IPF
- Subpleural and BASAL
- Reticular
- Honeycombing
- Absent of other features (ground glass, nodes, air trapping)
- Traction bronchiectasis
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CT related ILD
- UIP, but better prognosis
- Less fibroblast foci
- Younger age
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Causes of death in UIP
- Carcinoma (10 fold risk)
- Cor pulmonale
- Pulmonary HTN
- Respiratory failure
- Infection
- Exacerbation
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Histology of IPF
- Subplural heterogenous temporal and spatial
- Microscopic honeycombing
- Traction bronchiectasis
- Fibroblastic foci show young (temporal heterogeneity)
- Central sparing lobules
- By the way, cobblestoned on gross pathology
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Hypersensitivity Pneumonitis
- Bird fanciers
- Apical predominant consolidations
- Ground glass
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Prognosis of IPF
- 25% rapid progressive 3 year mortality
- 25% slow until acute exacerbation, probably 10 years
- 50% IPF with emphysema 5 years
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Treatment of IPF
- Pirfenidone or Nintedanib
- Corticosteroids unproven efficacy, often perscribed
- Oxygenation
- Pulm rehab
- Lung transplantation in selective patients
- Paliative care
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Sarcoidosis
- Non caseating granuloma, which can form nodules
- African American Women
- Steroids or self limited
- Trees in bud
- Hilar shadows
- Traction bronchiectasis
- Bronchoscopy
- Indistinguishable from Berylliosis (history!)
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Diffuse Alveolar Damage Pathogenesis
- Acute from any insult
- Early exudative phase: Hyaline membranes
- Organizing phase: organization and collagen
- Can present histologically as AIP, acute interstitial pneumonitis
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Determing cause of DAD
- Look for the obvious like bacteria means bacterial cause
- Neutrophils suggest infection
- Eosinophils-pneumonia
- Granulomas-anything
- Foamy macrophages-drug (amiodarone)
- Diffuse hemorrhage and capillaritis-vasculitis
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DAD prognosis
- 80% survival
- Worse with comorbidities
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Pathogenesis of organizing pneumonia
- Sub acute from any insult
- Can be idiopathic-cryptogenic organising pneumonia
- Minor component of many other diseases
- Consolidation (ie pneumonia)
- No hyaline membranes
- Branching appearance of granulation
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Prognosis of OP
- If idiopathic 70-90%
- Secondary dependent on cause
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NSIP is seen in
- Hypersensitive pneumonitis
- Drug induced
- CT diseases
- Idiopathic NSIP
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NSIP
- Homogenous
- Ground glass
- No honeycombing
- Fibrotic type or cellular
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NSIP prognosis and treatment
- Better than UIP
- Cellular more treatable (steroids)
- Fibrotic not as bad as UIP
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Causes of Granulomatous Lung Diseases
- Hypersensitivity pneumonitis
- Fungal, mycobacterial
- Aspiration
- Berylliosis
- Drug
- Idiopathic is sarcoidosis
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Causes of hypersensitivity pneumonitis
- Extrinsic allergic alveolitis
- Inhaled antigen or offending agent
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Diagnosis of HP
- BAL with lymphocytosis (40%+)
- Antibodies in serum
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Classification of HP
- Acute: 4-6 hours after exposure, lasts 48 hours (dyspnea)
- Subacute: Insidious over weeks to months (mildly restrictive)
- Crhonic: Insidious leading to fibrosis (restrictive)
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Histology of HP
- Centrilobular fibrosis
- Reticulation
- Menimal honeycombing
- Ground glass
- Granulomas and giant cells around bronchioles
- Chronic can be UIP, NSIP, centrilobular or combo
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Prognosis of HP
- Avoid the antigen
- Acute/subacute resolve
- Chronic has poor prognosis
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