Interstitial and occupational lung disease Flashcards
Broadly, what is interstitial lung disease?
Any disease process that affects the lung interstitium (alveoli and terminal bronchi)
It is therefore a disease that interferes with gas transfer and shows a restrictive lung pattern with symptoms of breathlessness and dry cough
What are the three types of ILD?
Acute
Episodic
Chronic - part of systemic disease, exposure to agent, idiopathic
What drug can cause ILD?
Methotrexate and nitrofuratonin
What is sarcoidosis?
Granulomatous (type 4 sensitivity) disease of unknown cause
Involves the lungs, lymph nodes, joints, liver, skin and eyes
Non-caseating granuloma of unknown aetiology
What are some symptoms of acute sarcoidosis?
Erythema nodosum Bilateral hilar lymphadenopathy Arthritis Uveitis Parotitis Fever
What are some symptoms of chronic sarcoidosis?
Lung infiltrates (alveolitis)
Skin infiltrations
Peripheral lymphadenopathy
Hypercalcaemia
What is the differential diagnosis in some suspected having sarcoidosis?
TB, lymphoma, carcinoma, fungal infection
How is sarcoidosis diagnosed?
CXR (bilateral hilar lymphadenopathy) CT scan of lungs (peripheral nodular infiltrate)
Tissue biopsy (transbronchial, skin, lymph node), non-caseating granulmona
Restrictive function on pulmonary function test
Blood test: angiotensin converting enzyme (ACE) levels as activity marker (NOT diagnostic test)
Raised calcium
Increased inflammatory markers
What is the treatment of sarcoidosis?
Acute: self-limiting usually no treatment
Steroids if vital organs are affected (e.g. impaired lung function, heart, eyes, brain, kidneys)
Chronic: oral steroids
Immunosuppresion (methotrexate, anti-TNF therapy)
Monitor CXR and pulmonary function tests
What is erythema nodosum?
Red patches of tender nodules which will fade and bruise
What is uveitis?
The anterior chambers of the eye fill up with inflammatory materials causing glaucoma and permanent damage - needs urgent referral to eye clinic
Treated with steroid drips
What are the granulomas in sarcoidosis composed of?
Epithelioid histiocytes Multinucelated giant cells Lymphocytes Plasma cells Fibroblasts Collagen
What is EAA?
Type 3 hypersensitivity (immune complex disposition) reaction to antigens
Aetiology: thermophilic actinomycetes (farmers lung, malt workers, mushroom workers), avian antigens (bird fanciers lung) drugs (gold, blemocycin, sulphasalazine)
What are the symptoms and treatment of acute EAA?
Cough, breathlessness, fever, myalgia (symptoms occur several hours after acute exposure)
Pyrexia, crackles (no wheeze), hypoxia
CXR: widespread pulmonary infiltrates
Treatment: oxygen, steroids, antigen avoidance
What are the symptoms of chronic EAA?
Repeated low dose antigen exposure over years with progressive breathlessness and cough
Crackles, clubbing unusual
CXR: pulmonary fibrosis in upper zones
Pulmonary function tests: restrictive defect
How is chronic EAA diagnosed?
History of exposure, precipitins (IgG antibodies to guilty antigen), lung biopsy if in doubt
How is chronic EAA treated?
Remove antigen exposure
Oral steroids if breathless or low gas transfer
What can cause IPF?
Aetiology of primary IPF not known
Secondary causes: rheumatoid, SLE (lupus), systemic sclerosis, asbestos, amiodarone, busulphan, belomycin, nitrofuraantoin, methotrexate
What is the clinical presentation of IPF?
Progressive breathlessness, dry cough, clubbing, bilateral fine inspiratory crackles
Restrictive defect on PFTs
Bilateral infiltrates on CXR
CT: Reticulondular fibrotic shadowing worse at bases and periphery
Traction bronchiectasis, honey-combing cystic changes
Lung biopsy
What is the differential diagnosis if IPF is suspected?
Occupational disease (asbestosis, silicosis), connective tissue disease, left ventricular failure, sarcoidosis, EAA
How is IPF diagnosed?
History
Examination
Radiology test (HRCT)
What is the pathology of IPF?
Usual Interstitial Pneumonia Pattern (UIP) with heterogenous fibrosis in alveolar walls with fibroblastic foci and the destructino of architecture causing honeycombing with minimal inflammation
How is IPF treated?
New antifibrotic drugs can slow down disease progression but is very expensive
Oxygen if hypoxia
Lung transplantation in young patients
Most patients progress within a few years into resp failure, median survival of IPF is 4 years from point of diagnosis
What is coal workers pneumoconiosis?
Simple pneumoconiosis - CXR abnormality only - no impairment of lung function
Compicated pneumoconiosis - progressive massive fibrosis, restrictive pattern with breathlessness
Chronic bronchitis - coal dust and smoking
What is caplan’s syndrome?
Exposure to coal dust can cause rheumatoid pneumoconiosis (pulmonary nodules, cavitating nodules in the lungs
What is silicosis?
15-20 years exposure to quartz
Simple pneumoconiosis - few symptoms, CXR abnormality (egg-shell calcification of hilar nodes)
Chronic silicosis - restrictive pattern, pulmonary fibrosis
What are some asbestol related lung disorders?
Pleural disease: benign pleural plaques - asymptomatic
Acute asbestos pleuritis - fever, pain, bloody pleural effusion
Pleural effusion and diffuse pleural thickening - restirctive impairement
Malignant mesothelioma - incurable pleural cancer, presents with chest pain and pleural effusion
Pulmonary fibrosis - diffuse pulmonary fibrosis and restrictive defect, asbestos bodies in sputum
Bronchial carcinoma
