Interstitial and Occupational Lung Disease (DISEASE MECHANISMS) Flashcards
What is interstitial disease?
Any disease that affects lung insterstitium, interferes with gas transfer and shows a restrictive lung pattern
What are the symptoms of ILD?
Breathlessness
Dry cough
What type of ILD would a viral infection cause?
Acute ILD
What can cause episodic ILD?
Environmental or systemic factors
What can cause chronic ILD?
Exposure to an external agent (drug, dust, etc.) or idiopathic
What is sarcoidosis?
Multi-system idiopathic non-caseating granulomatous type IV hypersensitivity disease
Which tissues does sarcoidosis commonly affect?
Lungs Lymph nodes Joints Liver Skin Eyes
Which tissues does sarcoidosis less commonly affect?
Kidneys
Brain
Nerves
Heart
What is the common presentation of acute sarcoidosis?
Uveitis Erythema nosodum BHL Arthritis Parotitis Fever
What is the common presentation of chronic sarcoidosis?
Lung infiltrates (Alveolitis)Skin infiltrations
Peripheral lymphadenopathy
Hypercalcaemia
Other organ involvement
What would be included in the differential diagnosis for sarcoidosis?
Tuberculosis
Lymphoma
Carcinoma
Fungal infection
How can you test for sarcoidosis?
CXR CT scan thorax Tissue biopsy Pulmonary function tests Blood tests
What would a CR of a sarcoidosis patient show?
BHL
What would a CT scan thorax of a sarcoidosis patient show?
Peripheral nodular infiltrate
What would a tissue biopsy of a sarcoidosis patient show?
Non-Caseating granuloma (diagnostic)
What type of lung pattern do sarcoidosis patients have?
Restrictive
What would be the expected blood test results be a for a sarcoidosis patient?
Increase ACE
Increased Ca
Increased Immunoglobulins
How is acute sarcoidosis treated?
Self-limiting
Bed Rest
NSAIDs (e.g. aspirin)
How is chronic sarcoidosis treated?
Oral steroid if vital organs affected
Immunosuppressants in severe illness
What type of follow-up should sarcoidosis patients receive?
Monitoring of CXR and pulmonary function for years to check for possible relapse
What are the indications for corticosteroids in sarcoidosis?
Parenchymal lung disease
Uveitis
Hypercalcaemia
Neurological or cardiac involvement
What is extrinsic allergic alveolitis?
Type III hypersensitivity reaction to an antigen
What are the causes of EAA?
Farmer’s and Mushroom’s lung (Micropolyspora faeni, Thermoactinomyces vulgaris)
Malt worker’s lung (aspergillus cluvatus)
Bagassosis or sugar worker’s lung (Thermoactinomyces sacchari)
Drugs (Bleomycin, gold, sulphazalanine)
What are the clinical features of acute EAA?
Cough Breathless Myalgia Fever/Pyrexia Crackles Hypoxia
How is acute EAA treated?
Remove allergen Give O2 (35-60%) Then oral prednisolon (40mg/24h PO) followed by reducing dose
What tests can be undertaken for acute EAA?
Blood - FBC, increased ESR, ABGs, positive serum precipitins (indicate exposure only)
CXR - upper zone mottling/consolidation, hilar lymphadenopathy
PFTs - restrictive pattern
What would cause chronic EAA?
Recurrent low antigen exposure
What are the signs and symptoms of chronic EAA?
Progressive Dyspnoea Cough Crackles Weight loss Exertion dyspnoea Type I respiratory failure Cor pulmonale CXR - fibrosis (mainly upper zones) PFTs - restrictive
How can a diagnosis of chronic EAA be made?
History of exposure
Positive serum precipitins
Lung biopsy if doubt
BAL (Bronchial alveolar lavage) shows increased lymphocytes & mast cells
How is chronic EAA treated?
Avoid exposure to allergen or wear facemark for positive pressure helmet
Long-term steroids often achieve CXR + physiological improvement
What is idiopathic pulmonary fibrosis?
Unknown origin Imbalance of fibrotic repair system ?related to gastric reflux Not inflammatory More common in smokers
What are secondary causes of pulmonary fibrosis?
Rheumatoid SLE Systemic sclerosis Asbestos Drugs (amiodarone, bleomycin, penicillamine, nitrofurantoin, methotrexate)
What is the clinical presentation of IPF?
Progressive dyspnoea
Dry cough
What is found O/E for IPF?
Clubbing
Bilateral fine inspiratory crackles
What is found Ix for IPF?
Restrictive pattern on PFTs
CXR - bilateral infiltrates, reduced lung volume, bilateral zone reticulonodular shadows, honeycomb (if advanced)
CT - reticulonodular fibrosis shadowing, worse at lung bases and periphery / Traction bronchiectasis, honey-combing / cystic changes
Lung biopsy (only if CT not diagnostic
Bloods: ABGs (low PaO2, high PaCO2 if severe) / CRP increased, increased immunoglobulins / ANA (30% TVC) / Rheumatoid factor (10% +ve)
What would have to be excluded from the differential to confirm IPF?
Occupational disease (asbestosis, silicosis)
Connective tissue disease (Rha, scleroderma, Sjorgens disease, SLE)
LVT
Sarcoidosis
EAA
How is the diagnosis of IPF made?
Combination of history, examination and HRCT scan (radiology)
What is the pathology of IPF?
Usual interstitial pneumonia pattern: heterogeneous fibres fibrosis in alveolar walls with fibroblastic foci and destruction of architecture causing honeycombing.
Inflammation is minimal
How is IPF treated?
Antifibrotic drugs (slow progression, no reversal) are in clinical trials
No steroids or anti-inflammatories (unless doubt diagnosis)
lung transplant
Best supportive care: O2 if hypoxic, pulmonary rehabilitation, opiates, palliative care input
What is the prognosis of IPF patients?
50% 5yr survival rate
Range 1-20 years
What does coal worker’s simple pneumoconiosis show on CXR?
Abnormality
What is the effect of coal worker’s simple pneumoconiosis on lung function?
Often associated with COPD
No impairment of lung function
What does coal worker’s complicated pneumoconiosis cause?
Progressive massive fibrosis (PMF)
Dyspnoea
Eventually cor pulmonale
What kind of lung pattern do patient’s with coal worker’s complicated pneumoconiosis have?
Restrictive
What causes chronic bronchitis?
Coal dust + smoking
What is Caplan’s syndrome?
Association between rheumatoid arthritis, pneumoconiosis, and pulmonary rheumatoid nodules
What causes silicosis?
Inhalation of silica particles (exposure to quartz - usually over long time
What occupations is silicosis associated with?
Mining
Foundry workers
Glass workers
Boiler workers
How does simple pneumoconiosis silicosis present?
Few symptoms
CXR - egg-shell calcification of hilar nodes
How does chronic pneumoconiosis silicosis present?
Progressive dyspnoea
Increased incidence of TB
CXR - diffuse military or nodular patterning upper and mid zones + egg-shell calcification of hilar nodes
Spirometry – restrictive pattern
What causes baritosis?
Exposure to barium
What are asbestos related pleural diseases?
Benign pleural plaques
Acute asbestos pleuritis
Pleural effusion and diffuse pleural thickening
Malignant mesothelioma
What are non-pleural asbestos related diseases?
Asbestosis
Bronchial carcinoma
What symptoms do benign pleural plaques cause?
None
How does acute asbestos pleuritis present?
Fever
Pain
Bloody pleural effusion
How does pleural effusion and diffuse pleural thickening due to asbestosis present in terms of spirometry?
Restrictive impairment
What is malignant mesothelioma?
Incurable pleural cancer
How does malignant mesothelioma present?
Chest pain
Pleural effusion
What is the average prognosis for malignant mesotheliomas
2 years
What colour is chrysotile asbestos?
white
What colour is amosite asbestos?
brown
What colour is crocidolite asbestos?
blue
In which order do the different colours of asbestos rank for increasing fibrogenicity?
White - brown - blue
What are the clinical features of asbestosis?
Progressive dyspnoea Clubbing Fine end-inspiratory crackles Pleural plaques Increased risk of bronchial adenocarcinoma and mesothelioma
The fact that smokers that have been exposed to asbestos have a higher risk for lung cancer than the sum of asbestos and smoker risk is called the ______?
Synergistic effect
Which occupations are related to asbestos exposure?
Mining
Construction
Ship-building
Boilers and piping
