Interstitial Lung Disease Flashcards
What happens (in general) in interstitial lung disease?
Inflammation and fibrosis of the interstitium
What is the lung interstitium?
The potential space between the alveolar epithelium and capillary endothelium
What cells are involved in ILD?
Epithelial Endothelial Mesenchymal Macrophages Recruited inflammatory cells
What type of deficit is ILD? Restrictive or obstructive? How?
Restrictive
-makes lungs less compliant due to development of the fibrous tissue
How is airway resistance affected in ILD?
It isn’t
Can sometimes be increased
What impairs gas exchange in ILD?
The lengthened diffusion pathway between alveolar air and blood impairs gas exchange
Clinical features of ILD?
4 D's Dry cough Progressive dyspnoea Digital clubbing Diffuse inspiratory crackles
Reduced exercise tolerance Tachypnoea Tachycardia Bilateral reduced chest movement Cyanosis and signs of right heart failure
Common general causes of ILD?
Occupational Treatment relayed Connective tissue disease Immunological Idiopathic
What are lung function results?
Show restrictive patterns.
FEV1/FVC is normal (>70%)
What is fibrosing alveolitis?
A progressive inflammatory condition of the lungs
Cause unknown
What happens histologically in fibrosing alveolitis?
Activated alveolar macrophages attract neutrophils and eosinophils
Lung damage due to ROS and proteases
Causes tissue destruction and fibrosis
Symptoms of fibrosing alveolitis?
Shortness of breath
Dry cough
Finger clubbing
What is seen on a CXR of fibrosing alveolitis?
Small lungs
Micro-nodular shadowing in lower lobes
Ragged heart borders
How is fibrosing alveolitis managed?
High dose oral steroids
Less effective once fibrosis has developed
What is extrinsic alveolitis?
A condition which results from repeated exposure to antigens of which the individual has been sensitised?
What are some examples of allergens in extrinsic alveolitis?
Mouldy hay (farmer’s lung)
Bird faeces (pigeon fancier’s lung)
Cotton fibres
Sugar cane fibres
What happens in extrinsic allergic alveolitis?
Lymphocytes and macrophages infiltrate small airways after exposure
Can either resolve or lead to pulmonary fibrosis
What happens in acute extrinsic alveolitis for eg farmer’s lung?
Exposed to allergen (thermophilic atinomyecytes)
Flu-like illness 4-9 hrs later with a dry cough and breathlessness on exertion
Fine mid and late inspiratory crackles
May be a wheeze
What is seen in chronic extrinsic allergic alveolitis?
Insidious malaise
Dry cough and breathlessness over months/years
Inspiratory crackles
What do lung function tests of extrinsic allergic alveolitis show?
Reduced compliance and reduced gas transfer
What is asbestosis?
Interstitial lung disease caused by asbestos
What is inhalation of asbestos associated with?
Benign pleural plaques
Mesothelioma
Asbestosis
Lung cancer
Pathology of asbestosis?
Asbestos fibres are breathed in and penetrate alveoli to cause alveolitis.
Influx of macrophages which form characteristic asbestosis bodies
Signs and symptoms of asbestosis?
Increased dyspnoea and exercise intolerance
Dry cough
Inspiratory crackles at lung bases which rise as the disease progresses
Lung function tests show small lungs, reduced compliance and impaired has transfer.
Treatment of asbestosis?
There is none
What is sarcoidosis?
A multi-system chronic inflammatory condition characterised by formation of epitheloid (macrophage) non-caseating granulomas at various sites in the body, commonly the lungs
What cells do alveoli contain in sarcoidosis?
Lots of macrophages and lymphocytes
What is seen on a CXR for sarcoidosis?
Miliary and modular shadowing
Diffuse fibrosis
Treatment of sarcoidosis?
Steroids are usually effective in suppressing disease for stages 1-3
What is seen in a lung function test for sarcoidosis?
Small lungs
Reduced compliance
Impaired gas transfer
May be airflow obstruction
Name some occupation ska lung diseases and the environmental factors associated with it
Asthma - lab workers - rat urine
Diffuse fibrosis - boiler/pipe laggers, railway, construction - asbestos
Modular fibrosis - coal minor, demolition - coal dust, silica, asbestos
Alveolitis - farmer, pigeon fancier - fungal spores from hay, avian antigens
What is seen in a CXR a for asbestosis?
Holly leaf plaques
Fibrosis
Mesothelioma
What is seen on a CXR for acute and chronic extrinsic allergic alveolitis?
Acute - micro-nodule infiltrate, denser towards hila
Chronic - almost normal, progresses to fibrosis in later stages.
What drugs can lead to ILD?
Methotrexate (rheumatoid arthritis)
Bleomycin (lymphoma treatment)
Amiodarone (arrhythmias)
Nitrofurantoin (antibiotic, UTIs)
What are the immunological causes of ILD?
Sarcoidosis
Hypersensitivity pneumonitis
What are some occupational causes of ILD?
Asbestosis
Silicosis
Coal workers pneumoconiosis
