*Interstitial and Occupational Lung Diseases 1 (lecture 1, 2 and 3) Flashcards
What are interstitial diseases of the lung?
Any disease process affecting the lung interstitium/ parenchyma in a diffuse manner i.e. alveoli and terminal bronchi
So interstitial diseases have a restrictive or obstructive lung pattern?
Restrictive
What are the characteristic features of interstitial lung disease in terms of the lung tissue?
Chronic inflammation
+/- progressive interstitial fibrosis
2 main symptoms of an interstitial lung disease?
Breathlessness
Dry cough
What are the 3 main categories, in terms of time, of interstitial lung disease?
Acute
Episodic
Chronic (part of systemic disease, exposure to agent, idiopathic)
What are the 4 main types of interstitial lung diseases?
ILD of known cause or association
Idiopathic interstitial pneumonia
Granulomatous ILDs
Other forms of ILD
How is idiopathic interstitial pneumonia categorised?
Either idiopathic pulmonary fibrosis
Idiopathic Interstitial pneumonia that isn’t IPF
What are the 6 causes of idiopathic interstitial pneumonia that are not idiopathic pulmonary fibrosis?
Desquamative interstitial pneumonia
Respiratory bronchiolitis interstitial lung disease
Acute interstitial pneumonia
Cryptogenic organising pneumonia
Lymphocytic interstitial pneumonia
Non-specific interstitial pneumonia (NSIP)
What are the 2 most important granulomatous ILDs to remember?
Sarcoidosis
Extrinsic allergic alveolitis
What is sarcoidosis?
A granulomatous disease of unknown cause
What type of hypersensitivity reaction is sarcoidosis?
Type 4
What systems are commonly affected by sarcoidosis? (6)
What systems are less commonly affected by sarcoidosis? (4)
Commonly:
Lungs, lymph nodes, joints, liver, skin, eyes
Less commonly:
Kidneys, brain, nerves, heart
Are the granulomas in sarcoidosis caseating or non-caveating?
non-caseating
TB = caseating
Is sarcoidosis more or less common in smokers?
Less
What are the 2 types of sarcoidosis?
Acute
Chronic
What are the symptoms of acute sarcoidosis?
Erythema nodosum Bilateral hilar lymphadenopathy Arthritis Uveitis, parotitis Fever (patient will feel generally unwell)
Symptoms of chronic sarcoidosis?
Lung infiltrates (alveolitis) Skin infiltrations Peripheral lymphadenopathy Hypercalcaemia Other organs = renal, myocardial neurological, hepatitis, splenomegaly (symptoms come on more insidiously)
Investigations for sarcoidosis? (5)
Chest x-ray (BHL)
CT scan of lungs (peripheral nodular infiltrate)
Tissue biopsy (e.g. transbronchial, skin, lymph node) for non-caeseating granuloma
Pulmonary function (restrictive lung pattern)
Blood tests (ACEI as activity marker - not diagnostic test, raised calcium, raised inflammatory markers)
Treatment of acute sarcoidosis?
Self-limiting condition = usually no treatment required - steroids if vital organ affected
Treatment of chronic sarcoidosis?
Ora steroids usually needed
Immunosupression e.g. aathioprine, methotrexate, anti-TNF therapy
(monitor chest x-ray and pulmonary function for several years as often relapses)
What is another name for extrinsic allergic alveolitis?
Hypersensitivity pneumonitis
What type of hypersensitivity is extrinsic allergic alveolitis?
Type III hypersensitivty (predominantly - there is also a type 4 reaction)
What happens in extrinsic allergic alveolitis?
In sensitised individuals, inhalation of allergens (fungal spores, thermophilic bacteria or avian proteins) causes a hypersensitivity reaction
In the acute phase, alveoli are infiltrated with acute inflammatory cells
With chronic exposure, granulomas form and obliterative bronchiolitis occurs
Types of extrinsic allergic alveolitis caused by exposure to protein in avian droplets?
Bird fanciers lung
Pigeon fanciers lung
Type of extrinsic allergic alveolitis due to exposure to aspergillus clavatus?
Malt workers lung
Type of extrinsic allergic alveolitis due to exposure to micropolyspora faeni usually seen in farmers caused by mouldy hay?
Farmers lung
Type of extrinsic allergic alveolitis typically seen in people who work with mushrooms due to exposure to thermoactinomyces vulgaris?
Mushroom workers lung
Drugs that can cause extrinsic allergic alveolitis? (3)
Gold
Bleomycin
Sulphasalazine (rheumatoid arthritis)
(no cause identified in approx 30% of cases of extrinsic allergic alveolitis)
2 types of extrinsic allergic alveolitis?
Acute
Chronic
Symptoms of acute extrinsic allergic alveolitis?
Onset of symptoms?
Cough Breathlessness Fever Myalgia Classical several hours after acute exposure
Signs of acute extrinsic allergic alveolus?
+/- pyrexia
Crackles (no wheeze)
Hypoxia
Appearance of a chest x-ray in a patient with acute extrinsic allergic alveolitis?
Widespread pulmonary infiltrates
Treatment of extrinsic allergic alveolitis?
Oxygen
Steroid
Antigen avoidance
What causes chronic extrinsic allergic alveolitis?
Repeated low dose antigen exposure over time (years) leading to progressive breathlessness and a cough
Signs of chronic extrinsic allergic alveolitis?
Crackles - clubbing is unusual
Appearance of chronic extrinsic allergic alveolitis on a chest x-ray?
Pulmonary fibrosis - most commonly in the upper zones
Diagnosis of chronic extrinsic allergic alveolitis?
History of exposure, preciptins (IgG antibodies to guilty antigen), lung biopsy if in doubt
Treatment of chronic extrinsic allergic alveolitis?
Remove antigen exposure
Oral steroids if breathless or low gas transfer
Causes of fibrosis in the upper zones?
TB Extrinsic allergic alveolitis Ankylosing spondylitis Radiotherapy Sarcoidosis
Causes of fibrosis in the middle zones?
Progressive massive fibrosis
Causes of fibrosis in the lower zone?
Idiopathic pulmonary fibrosis
Asbestosis
Former name of idiopathic pulmonary fibrosis? (2)
Cryptogenic fibrosing alveolitis
Also known as usual interstitial pneumonia
What is the most common interstitial lung disease?
IPF
What is idiopathic pulmonary fibrosis?
Inflammatory cell infiltrate and pulmonary fibrosis of unknown cause (not predominantly an inflammatory condition and therefore doesn’t respond well to steroids)
What is thought to be the cause of IPD?
imbalance of fibrotic repair mechanism - the lung is trying to repair itself by laying down scar tissue when there is nothing to be repaired
Is IPF more or less common in smokers?
More
Secondary causes of pulmonary fibrosis that my be ruled out before diagnosing idiopathic pulmonary fibrosis?
Rheaumatoid, lupus, systemic sclerosis, asbestos, drugs
What drugs can cause pulmonary fibrosis?
Amiodarone - anti-arrhythmic Busulphan - cancer drug Bleomycin Penicillamine - wilsons disease Nitrofuratoin -antibiotic for UTIs Methotrexate - cancer, etc.
Symptoms and signs of idiopathic pulmonary fibrosis?
Progressive breathlessness (several years), dry cough Clubbin, bilateral fine inspiratory crackles
Investigations for IPF? (4)
PFTs (restrictive pattern)
CxR (bilateral infiltrates)
CT scan (reticulonodular fibrotic change)
Lung biopsy - not needed if CT is diagnostic
What is a reticular interstitial pattern?
Complex network of opacities that normally affect the lung diffusely
Reticulonodular interstitial pattern?
produced by either, overlap of reticular shadows, or by the presence of reticular shadowing and pulmonary nodules.
3 types of reticular interstitial pattern?
fine “ground-glass” (1-2 mm): seen in processes that thicken the pulmonary interstitium to produce a fine network of lines, e.g. interstitial pulmonary oedema
medium “honeycombing” (3-10 mm): commonly seen in pulmonary fibrosis with involvement of the parenchymal and peripheal interstitium
coarse (> 10 mm): cystic spaces caused by parenchymal descruction, e.g. usual interstitial pneumonia, pulmonary sarcoidosis, pulmonary Langerhans cell histiocytosis
What does the presence of a ground glass fibrotic change indicate?
Reversible alveolitis - fibrosis is irreversible
What would the pathological appearance of idiopathic pulmonary fibrosis be?
Chronic inflammatory infiltrate (neutrophils and fibrosis in alveolar walls +/- intra-alveolar macrophages)
Treatment of IPF?
Supportive therapy e.g. O2, opiates, palliative care
N-acetyl cistein may have anti-fibrotic effects via its anti-oxidant properties
Pirfenidone is a new antifibrtoic drug that slows down the progression of the disease but very expensive
If the patient is young = lung transplant
What is pneumoconiosis?
a disease of the lungs due to inhalation of dust, characterized by inflammation, coughing, and fibrosis.
What is coal workers pneumoconiosis?
A common dust disease resulting from inhalation of coal dust particles over 15- 20 years - ingested by macrophages which die, releasing their enzymes and causing fibrosis
What is simple pneumoconiosis? (coal workers pneumoconiosis)
A chest x-ray abnormality (no impairment of the lung function) - often with coexisting chronic bronchitis
What is progressive massive fibrosis?
Due to progression of CWP - restrictive pattern with breathlessness
Caplan’s syndrome?
The association between rheumatoid arthritis, pneumoconiosis and pulmonary rheumatoid nodules
What is silicosis?
Occupational lung disease caused by inhalation of silica particles (can be wither simple or chronic)
Simple silicosis?
Chest x-ray abnormality only (egg shell calcification of hillier nodes)
Chronic silicosis?
Restrictive pattern, pulmonary firbossi
What 3 categories of disease can asbestos cause?
Pleural disease
Pulmonary fibrosis
Bronchial carcinoma (asbestos multiplies risk in smokers)
What 4 diseases of the pleura can asbestos cause?
Benign pleural plaques - asymtpomatic
Acute asbestos pleuritic - fever, pain, bloody pleural effusion
Pleural effusion and diffuse pleural thickening - restrictive impairment
Malignant mesothelioma
What is the name for pulmonary fibrosis due to asbestos exposure?
Diagnosis?
Asbestosis - heavy prolonged exposure hisotry, diffuse pulmonary fibrosis and restrictive defect, asbestos bodies in sputum, asbestos fibres in lung biopsy
What is the pulmonary interstitium made up of? (2)
Alveolar lining cells (types 1 and 2)
Thin elastin-rich connective component containing capillary blood vessels
In terms of pathology, what are the 2 stages of interstitial lung disease?
Early stage = alveolitis (injury with inflammatory cell infiltration)
Late stage = fibrosis
What type of heart failure is associated with late stage lung disease?
Right sided heart failure
What are the 2 possible types of biopsy that can be take for interstitial lung disease?
Transbronchial biopsy
Thoracoscopic biopsy - more invasive but more reliable and generates more tissue
What are the main types of chronic interstitial diseases?
Pulmonary fibrosis (fibrosing alveolitis) Sarcoidosis Extrinsic allergic alveolitis Pneumoconiosis Connective tissue diseases
Where about does the fibrosis caused by idiopathic pulmonary fibrosis occur?
Subpleural
Basal fibrosis
What is honeycomb lung?
the radiological appearance seen with widespread fibrosis and is defined by the presence of small cystic spaces with irregularly thickened walls composed of fibrous tissue = poor prognosis (dilated spaces surrounded by fibrous walls)
Types of asbestos fibres from most to least fibrogenic?
Crocidolite (blue) = most (straight - amphibole)
Amosite (brown) = intermediate
Chrysotile (white) = least (curved - serpentine)
What are the 2 basic types of occupational lung disease?
Extrinsic allergic alveolitis
pneumoconiosis
What is the type of EAA caused by exposure to loudly sugar cane fibre - thermoactinomyces saccharin?
Bagossosis/ sugar handlers lung
What is the type of EAA caused by exposure to contaminated forced-air systems/ heated water reservoirs - s rectivigula/ T vulgaris?
Humidifier/ air-conditioner lung
What is the type of EAA caused by exposure to cheese mould? (penicillin casei)
Cheese worker’s lung
How lung after exposure to asbestos does mesothelioma develop?
Over 20 years (usually 30 - 40)
What 2 factors added together have a synergistic effect on increasing chance of developing lung cancer?
Smoking
Asbestos exposure
What type of conditions cause mould to grow in houses?
Damp and cold conditions
Environmental sources of lung disease? (not occupational)
Asbestos Mould Cooking smoke Passive smoking Air/ traffic pollution Nanoparticles
What are dioxins?
A sub-set of persistent organic compounds that are associated with reproductive and immunological problems - bioaccumulates in people and animal fat (at least 90% come from out diet)
What is a notifiable disease?
A notifiable disease is any disease that is required by law to be reported to government authorities e.g. legionella
