Interstitial Lung Disease Flashcards
Causes of interstitial lung disease.
Usual interstitial pneumonia (UIP)
Non-specific interstitial pneumonia (NSIP)
Extrinsic allergic alveolitis/Hypersensitivity Pneumonitis
Sarcoidosis
etc…
What is the most common cause of pulmonary fibrosis?
UIP
What is the most common cause of idiopathic interstitial pneumonias?
Idiopathic pulmonary fibrosis
What is the difference between usual interstitial pneumonia and idiopathic pulmonary fibrosis?
Usual interstitial pneumonia is the pathological pattern seen in e.g. idiopathic pulmonary fibrosis.
Idiopathic pulmonary fibrosis is the clinical diagnosis.
However not all UIP should be diagnosed as IPF.
UIP can also be seen in other diffuse parenchymal lung diseases such as pulmonary autoimmune rheumatic disease.
However to simplify things, in these flashcards IPF and UIP might be used interchangeably.
Clinical features of IPF.
Age > 50
Male > female
Progressive dyspnoea >3 mo
Progressive dry cough >3 mo
Respiratory failure
Hx of smoking
Examinatory findings in IPF.
Resp failure
Clubbing
Cyanosis
Fine inspiratory crackles bi-basally.
Raynaud’s
Cor pulmonale
When is clubbing seen in IPF.
In advanced disease
25-50% of cases
Not seen in drug induced ILD.
If there is new onset of finger clubbing, what should be considered?
Lung cancer
Investigations done in IPF.
Diagnosis is based on clinical features and HRCT
Who needs lung biopsy in IPF?
Most don’t as HRCT is usually confirmatory.
Young patients
Atypical clinical examination
Atypical radiological features
To rule out malignancy if there is suspicion of it.
Diagnostic approach of IPF.
HRCT
Final diagnosis is a combination of radiological, clinical and serological findings.
If still uncertain an MDT meeting will confirm whether a lung biopsy should be performed.
Explain the pathogenesis of IPF.
Repeated cycles of epithelial activation by some unidentified agent.
Dysregulated repair process
Inflammatory pathways leading to fibrosis
Abnormal epithelium reapir leading to abnormal fibroblastic foci.
Drugs that can cause IPF.
Amiodarone
Methotrexate
Bleomycin
Radiation
Nitrofurantoin
Cyclophosphamide
Diseases associated with IPF.
HS pneumonitis
RA
SLE
Scleroderma
Radiation therapy
Alpha-1 antitripsin deficiency
Findings on biopsy in IPF.
Cobblestone surface of the lung
Fibroblastic foci
Heterogeneity on histology.
CXR findings in IPF.
Small volume lungs
Reticulonodular shadowing
HRCT findings in IPF.
Basal distribution
Ground glass appearance
Honeycomb appearance in advanced disease
Reticulonodular shadowing
Traction bronchiectasis
Image shows a fibrotic lung (r) and a transplanted healthy lung (L)
When might a bronchoalveolar lavage be done to investigate ILD?
If there is an infective or malignant cause suspected.
Findings on PFT in IPF.
Reduced FVC
Increased FEV1/FVC ratio or preserved
Reduced TLC
Reduced transfer factor
Treatment aims in IPF.
Median survival time for patients with IPF is 2-5 years. The mortality is increased following acute exacerbations.
Symptom relief
Slow progression
Prevent complications
Improve QOL
Prolong survival
Prevent treatment complications
End of life care
Treatment of IPF.
Antifibrotic drugs such as perfenidone or nintedanib.
Treat co-morbidities
Pulmonary rehab
O2 therapy
Opiates
Palliative care
Generally discourage use of immunosuppression
When should perfenidone be given?
In UIP and FVC between 50-80%.
Explain mechanism of action of nintedanib.
Intracellular inhibition of multiple tyrosine kinases
Complications of IPF.
Resp failure
Pulm HTN
Acute exacerbation
Resp infection
ACS
Thromboembolism
Lung cancer
Adverse tx effects
Occupational causes of ILD.
Asbestosis
Silicosis
Coal worker’s pneumoconiosis
Pigeon workers/fanciers
Hypersensitivity pneumonitis
Investigations of ILD (immunological)
ANA
ENA
Rh F
ANCA
Anti-GBM
ACE
IgG
HIV
What is extrinsic allergic alveolitis also called?
Hypersensitivity pneumonitis
Explain EAA
Type III HS reaction to an environmental allergen that causes parenchymal inflammation and destruction in people that are sensitive to that allergen.
Bronchoalveolar lavage involves collecting cells from the airways during bronchoscopy by washing the airways with fluid then collecting that fluid for testing. This shows raised lymphocytes and mast cells in hypersensitivity pneumonitis..
Causes of EAA.
Farmer’s lung (mould in hay) and Bird-fancier’s/Pigeon-fancier’s (reaction to bird droppings) lung are the most common causes.
Mushroom worker’s lung
Malt worker’s lung (mould)
Bagassosis
Clinical features of EAA.
Depends on whether it is acute or chronic.
Clinical features of acute EAA.
4-8h post exposure.
Fever, rigors, myalgia, dry cough, dyspnoea and fine bi-basal crackles.
This is usually reversible and spontaneously settle within 1-3 days.
Clinical features of chronic EAA.
Finger clubbing (50%)
Increasing dyspnoea
Decreased weight
Extertional dyspnoea
Type 1 resp failure
Cor pulmonale
Pathogenesis of EAA.
Chronic inflammatory infiltrates and poorly defined interstitial granulomas together with interstitial fibrosis and honeycomb change in chronic disease.
Cellular immmunity and deposition of immune complexes causing foci of inflammation through activation of complement via the classical pathway.
Investigations in EAA.
Bloods - FBC (neutrophilia), raised ESR, ABGs, serum antibodies.
CXR
HRCT
PFTs
Bronchoalveolar lavage
What does serum antibodies tell you about EAA?
It does not necessarily suggest disease but purely exposure or previous sensitisation to allergen.
Findings on CXR in acute EAA.
May be normal.
If abnormal you might see diffuse small nodules and increased reticular shadowing.
Upper-zone mottling.
Findings on PFTs in acute EAA
These are not diagnostic.
However can should reversible restrictive lung disease.
Reduced gas transfer
CXR/HRCT findings in chronic EAA.
Upper-zone fibrosis
Honeycomb lung.
Ground glass opacities
Increased reticular shadowing.
In some cases, it may be difficult to differentiate from idiopathic pulmonary fibrosis - UIP cases are also thought to have honeycombing and peripheral or lower lung zone predominance of disease, and less likely to have micronodules 4.
HRCT findings on chronic EAA.
Nodules
Ground glass appearance
Increased reticulation
Honeycomb lung
Extensive fibrosis
This is all usually seen in the mid or upper zones of the lungs.
What will bronchoaleolar lavage show in EAA?
Increased lymphocytes and increased mast cells.
Management of acute EAA.
Remove allergen and give O2 (35-60%)
PO prednisolone 40mg/24h as a reducing course
Management of chronic EAA.
Remove allergen
Wear a facemask or +ve pressure helmet.
Long-term steroids often achieve CXR and physiological improvement.
Azathioprine or cyclophosphamide might be used.
Causes of fibrotic shadowing on CXR in the upper zone.
TB
HS pneumonitis
Ankylosing spondylitis
Radiotherapy
Progressive massive fibrosis
Causes of fibrotic shadowing on CXR in the mid zone.
Sarcoidosis
Histoplasmosis
Causes of fibrotic shadowing on CXR in the lower zone.
Idiopathic pulmonary fibrosis
Asbestosis
