interstitial and occupational lung disease Flashcards
Does interstitial lung disease have an obstructive or restrictive pattern?
Restrictive
What are the two main symptoms of interstitial lung disease?
- breathlessness
- dry cough
What are three common interstitial lung diseases?
- idiopathic pulmonary fibrosis
- extrinsic allergic alveolitis
- sarcoidosis
Sarcoidosis:
- what type of hypersensitivity reaction is involved?
- what different systems are commonly (6)/less commonly involved (4)?
- what does it cause to develop?
- is it common in smokers or non-smokers?
- Granulomatous type 4 hypersensitivity reaction of an unknown cause
- common: lungs, lymph nodes, joints, liver, skin, eyes
- less common: kidney, brain, nerves, heart
- it causes a non-caseating granuloma of unknown aetiology
- less common in smokers
What 6 clinical features can be found in acute sarcoidosis?
- erythema nodosum
- bilateral hilar lymphadenopathy
- arthritis
- uveitis
- parotitis
- fever
What 4 clinical features can be found in chronic sarcoidosis?
- lung infiltrates (alveolitis)
- skin infiltrations
- peripheral lymphadenopathy
- hypercalcaemia
(other organs: renal, myocardial, neurological, hepatitis, splenomegaly)
What are 4 differential diagnoses for sarcoidosis?
- TB (tuberculin test -ve)
- lymphoma
- carcinoma
- fungal infection
what is seen on chest x ray, CT scan lungs and tissue biopsy for sarcoidosis?
CXR: bilateral hilar lymphadenopathy
CT: peripheral nodular infiltrate
Tissue biopsy: non-caseating granuloma
What blood tests are indicative for sarcoid?
Angiotensin converting enzyme (ACE) levels as activity marker (not diagnostic test)
Raised calcium
Increased inflamm. markers
What is the treatment for acute v chronic sarcoid?
Acute - self limiting, usually no treatment unless vital affected and then steroids are used (eg impaired lung function, heart, eyes, brain, kidneys)
Chronic - oral steroids usually needed, immunosuppression(eg azathioprine, methotrexate, anti-TNF therapy)
What kind of follow up is needed for patients diagnosed with sarcoidosis?
-monitor CXR and pulmonary function for several years as often relapses
Extrinsic allergic alveolitis AKA hypersensitivity pneumonitis:
- What type of hypersensitivty reaction is involved?
- what different aetiologies exist?
-Type 3 hypersensitivity reaction to an antigen
Aetiologies:
- thermophilic actinomycetes (farmers lung, malt workers, mushroom workers)
- Avian antigens (bird fanciers lung)
- drugs (gold, bleomycin, sulphasalazine)
No cause identified in about 30% cases
What are the clinical features of acute extrinsic allergic alveolitis?
What clinical signs are seen?
What is seen on CXR?
What is treatment?
-cough, breathless, fever, myalgia (Classically symptoms occur several hours after acute exposure (flu-like illness))
Signs: +/- pyrexia, crackles (no wheeze!), hypoxia
CxR: widespread pulmonary infiltrates
Treatment: oxygen, steroid and antigen avoidance
What are the clinical features of chronic extrinsic allergic alveolitis?
What clinical signs are seen?
What is seen on CXR?
What is seen on pulmonary function tests?
repeated low dose antigen exposure over time (years)
progressive breathlessness and cough
Signs: may be crackles, clubbing is unusual
CxR pulmonary fibrosis - most commonly in the upper zones
PFTs: restrictive defect (low FEV1 & FVC, high or normal ratio, low gas transfer - TLCO)
How is chronic extrinsic allergic alveolitis diagnosed? and what is the treatment?
Diagnosis: history of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if in doubt.
Treatment: remove antigen exposure, oral steroids if breathless or low gas transfer.
Idiopathic pulmonary fibrosis:
- what is the cause of primary IPF?
- What are some causes of secondary IPF? (5)
Aetiology unknown.
Secondary causes:
- Diseases e.g. Rheumatoid, SLE, systemic sclerosis, asbestos
- Drugs e.g. amiodarone, busulphan, bleomycin, penicillamine, nitrofurantoin, methotrexate
What are the clinical features of idiopathic pulmonary fibrosis (2)? Signs (2)? pulmonary function tests?
- Progressive breathlessness of several years, dry cough
- OE: clubbing, bilateral fine inspiratory crackles
PFTs: restrictive (reduced FEV1 and FVC = normal or raised FEV1/FVC ratio) reduced lung volumes, low gas transfer
in idiopathic pulmonary fibrosis what is seen on CXR? and CT scan? is lung biopsy needed?
CxR - bilateral infiltrates;
CT scan - reticulonodular fibrotic shadowing, worse at the lung bases, and periphery. Traction bronchiectasis. Honey-combing cystic changes.
lung biopsy – not necessary if CT scan is diagnositic.
What is the differential diagnosis for idiopathic pulmonary fibrosis? (7)
exclude occupational disease (asbestosis, silicosis), connective tissue disease (RhA, scleroderma, Sjogrens Disease, SLE), left ventricular failure, sarcoidosis, extrinsic allergic alveolitis.
(Ask about occupation (in depth), pets and drug history)
How is idiopathic pulmonary diagnosed?
Diagnosis: combination of history, examination and radiology tests (HRCT scan)
If the presentation or the HRCT scan is atypical then lung biopsy (either transbronchial or thoracascopic) may be needed
Describe the pathology seen in idiopathic pulmonary fibrosis
Usual Interstitial Pneumonia pattern (UIP) heterogenous fibrosis in alveolar walls with fibroblastic foci and destruction of architecture causing honeycombing. Inflammation is minimal.
What is the treatment for idiopathic pulmonary fibrosis?
What is the prognosis?
Treatment is frustrating.
Steroids and immunosuppressants do not change course of disease
New antifibrotic drugs have emerged in recent years – PIRFENIDONE and NINTEDANIB – only therapies to have shown in randomised controlled trials to slow down disease progression BUT very expensive, and many side-effects.
Antifibrotic therapy does not reverse fibrosis, merely slows progression
Oxygen if hypoxic.
Lung transplantation in young patients
Prognosis: most patients progress within a few years into respiratory failure
Median survival of IPF is 4 years from point of diagnosis
in coal workers pneumoconiosis what is the difference between simple and complex pneumoconiosis?
What two other clinical features are sometimes seen?
Simple pneumoconiosis - chest X-ray abnormality only (no impairment of lung function - often associated with chronic obstructive pulmonary disease).
Complicated pneumoconiosis - progressive massive fibrosis causing a restrictive pattern with breathlessness.
Also: Chronic bronchitis (coal dust + smoking).
Caplan’s syndrome - rheumatoid pneumoconiosis (pulmonary nodules). This is where there is a combination of rheumatoid arthritis (RA) and pneumoconiosis that manifests as intrapulmonary nodules
Silicosis:
How is this caused?
What is seen on CXR?
What is the difference between the simple pneumoconiosis and the chronic silicosis that is seen?
15-20 years exposure to quartz (eg mining, foundry workers, glass workers, boiler workers).
Simple pneumoconiosis – few symptoms; Chronic silicosis - restrictive pattern, pulmonary fibrosis.
chest X-ray abnormality (egg-shell calcification of hilar nodes).
Asbestosis:
-Describe the four stages of the pleural disease caused?
1- Benign pleural plaques - asymptomatic
2- Acute asbestos pleuritis - fever, pain, bloody pleural effusion
3- Pleural Effusion and Diffuse pleural thickening - restrictive impairment
4- Malignant Mesothelioma - incurable pleural cancer. Presents with chest pain and pleural effusion. No available treatment - fatal within two years.
Describe the pulmonary fibrosis seen in asbestosis:
- how is it caused?
- what is seen on pulmonary function tests?
- What other tests are useful?
“Asbestosis” - heavy prolonged exposure.
Diffuse pulmonary fibrosis and restrictive defect.
Asbestos bodies in sputum. Asbestos fibres in lung biopsy.
Apart from pleural malignancy what other malignancy does asbestos increase the risk of?
Bronchial carcinoma - asbestos multiplies risk in smokers
For interstitial lung disease in general describe how the pathology of the lung progresses?
- early stage is alveolitis (injury with inflammatory cell infiltration)
- late stage is characterised by fibrosis
What is the difference between transbronchial biopsy and thoracoscopic biopsy?
Transbronchial biopsy – special forceps used at bronchoscopy
Thoracoscopic biopsy – more invasive but more reliable and generates far more tissue
What is idiopathic pulmonary fibrosis AKA?
- cryptogenic fibrosing alveolitis
- usual interstitial pneumonia
What is the pathology seen in idiopathic pulmonary fibrosis?
Subpleural and basal fibrosis
Inflammatory component variable
Terminally lung structure replaced by dilated spaces surrounded by fibrous walls
What is pneumoconiosis? what are the three different types?
lung disease caused by mineral dust exposure:
- asbestosis
- coal workers lung
- silicosis
