Restrictive lung disease - Idiopathic pulmonary fibrosis Flashcards
What is idiopathic pulmonary fibrosis?
Also known as usual interstitial pneumonia (UIP) and was previously known as cryptogenic fibrosing alveolitis (CFA).
It is described as a chronic irreversible and ultimately fatal disease characterized by a progressive decline in lung function.
What is the pathogenesis of IPF?
Multiple injuries to the alveolar cells cause them to secrete growth factors that recruit fibroblasts in a fibrotic environment. These differentiate into myofibroblasts under the influence of TNF-beta, synthesize collagen and aggregate in fibrotic foci.
In essence, this is a remodelling response gone wrong, and results in heterogeneous irreversible fibrosis
What are the histological features of UIP?
- Patchy interstitial chronic inflammation
- Type II pneumocyte hyperplasia
- Proliferating fibroblastic foci
What are symptoms of UIP?
- Dry cough
- Exertional dyspnoea
- Malaise
- Weight loss
- Arthralgia
What are signs of UIP?
- Cyanosis
- Finger clubbing
- Fine-end inspiratory crepitations
How would you investigate someone who you suspected had UIP?
- Bloods - ABG, CRP, Immunoglobulin, ANA, RF
- CXR
- HRCT
- Spirometry and gas transfer
- BA lavage
- Lung biopasy
What might you see on ABG in someone with UIP?
- Type I respiratory failure - Decreased PaO2
- Type II respiratory failure in severe cases - Increased PaCO2
What happens to the CRP in someone with UIP?
Increased CRP
What inflammatory markers can be increased in UIP?
- ANA
- RF
- Immunoglobulins
- CRP
What might you see on CXR in someone with UIP?
- Decreased lung volume
- Bilateral lower zone reticulonodular shadows
- Honeycomb lung - advanced disease
What might you see on CT scanning in someone with UIP?
- Honeycombing
- Reticular opacities: subpleural lung - associated with honeycombing and traction bronchiectasis
- Ground-glass opacities
- Lung architectural distortion
- Lobar volume loss (predominantly lower lobes)
What will you see on spirometry and gas transfer in someone with UIP?
Restrictive lung pattern + reduced gas transfer
What might you see on BA lavage in someone with UIP?
Increased lymphocytes/neutrophils/eosinophils
What are complications of UIP?
- Respiratory failure
- Lung cancer risk
What is the differential diagnosis for someone with features of UIP?
- Hypersensitivity pneumonitis
- Bronchiectasis
- Chronic left heart failure
- Sarcoidosis
- Industrial lung disease
- Lymphangitis carcinomatosa