Interstitial Lung Disease Flashcards by Don J

Causes of interstitial lung disease.

Usual interstitial pneumonia (UIP)

Non-specific interstitial pneumonia (NSIP)

Extrinsic allergic alveolitis/Hypersensitivity Pneumonitis

Sarcoidosis

etc…

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What is the most common cause of pulmonary fibrosis?

UIP

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What is the most common cause of idiopathic interstitial pneumonias?

Idiopathic pulmonary fibrosis

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What is the difference between usual interstitial pneumonia and idiopathic pulmonary fibrosis?

Usual interstitial pneumonia is the pathological pattern seen in e.g. idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis is the clinical diagnosis.

However not all UIP should be diagnosed as IPF.

UIP can also be seen in other diffuse parenchymal lung diseases such as pulmonary autoimmune rheumatic disease.

However to simplify things, in these flashcards IPF and UIP might be used interchangeably.

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Clinical features of IPF.

Age > 50

Male > female

Progressive dyspnoea >3 mo

Progressive dry cough >3 mo

Respiratory failure

Hx of smoking

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Examinatory findings in IPF.

Resp failure

Clubbing

Cyanosis

Fine inspiratory crackles bi-basally.

Raynaud’s

Cor pulmonale

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When is clubbing seen in IPF.

In advanced disease

25-50% of cases

Not seen in drug induced ILD.

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If there is new onset of finger clubbing, what should be considered?

Lung cancer

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Investigations done in IPF.

Diagnosis is based on clinical features and HRCT

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Who needs lung biopsy in IPF?

Most don’t as HRCT is usually confirmatory.

Young patients

Atypical clinical examination

Atypical radiological features

To rule out malignancy if there is suspicion of it.

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Diagnostic approach of IPF.

HRCT

Final diagnosis is a combination of radiological, clinical and serological findings.

If still uncertain an MDT meeting will confirm whether a lung biopsy should be performed.

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Explain the pathogenesis of IPF.

Repeated cycles of epithelial activation by some unidentified agent.

Dysregulated repair process

Inflammatory pathways leading to fibrosis

Abnormal epithelium reapir leading to abnormal fibroblastic foci.

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Drugs that can cause IPF.

Amiodarone

Methotrexate

Bleomycin

Radiation

Nitrofurantoin

Cyclophosphamide

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Diseases associated with IPF.

HS pneumonitis

SLE

Scleroderma

Radiation therapy

Alpha-1 antitripsin deficiency

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Findings on biopsy in IPF.

Cobblestone surface of the lung

Fibroblastic foci

Heterogeneity on histology.

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CXR findings in IPF.

Small volume lungs

Reticulonodular shadowing

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HRCT findings in IPF.

Basal distribution

Ground glass appearance

Honeycomb appearance in advanced disease

Reticulonodular shadowing

Traction bronchiectasis

Image shows a fibrotic lung (r) and a transplanted healthy lung (L)

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When might a bronchoalveolar lavage be done to investigate ILD?

If there is an infective or malignant cause suspected.

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Findings on PFT in IPF.

Reduced FVC

Increased FEV1/FVC ratio or preserved

Reduced TLC

Reduced transfer factor

Treatment aims in IPF.

Median survival time for patients with IPF is 2-5 years. The mortality is increased following acute exacerbations.

Symptom relief

Slow progression

Prevent complications

Improve QOL

Prolong survival

Prevent treatment complications

End of life care

Treatment of IPF.

Antifibrotic drugs such as perfenidone or nintedanib.

Treat co-morbidities

Pulmonary rehab

O2 therapy

Opiates

Palliative care

Generally discourage use of immunosuppression

When should perfenidone be given?

In UIP and FVC between 50-80%.

Explain mechanism of action of nintedanib.

Intracellular inhibition of multiple tyrosine kinases

Complications of IPF.

Resp failure

Pulm HTN

Acute exacerbation

Resp infection

ACS

Thromboembolism

Lung cancer

Adverse tx effects

Occupational causes of ILD.

Asbestosis Silicosis Coal worker's pneumoconiosis Pigeon workers/fanciers Hypersensitivity pneumonitis

Investigations of ILD (immunological)

ANA ENA Rh F ANCA Anti-GBM ACE IgG HIV

What is extrinsic allergic alveolitis also called?

Hypersensitivity pneumonitis

Explain EAA

Type III HS reaction to an environmental allergen that causes **parenchymal inflammation** and **destruction** in people that are sensitive to that allergen. Bronchoalveolar lavage involves collecting cells from the airways during bronchoscopy by washing the airways with fluid then collecting that fluid for testing. This shows raised lymphocytes and mast cells in hypersensitivity pneumonitis..

Causes of EAA.

Farmer's lung (mould in hay) and Bird-fancier's/Pigeon-fancier's (reaction to bird droppings) lung are the most common causes. Mushroom worker's lung Malt worker's lung (mould) Bagassosis

Clinical features of EAA.

Depends on whether it is acute or chronic.

Clinical features of acute EAA.

4-8h post exposure. Fever, rigors, myalgia, dry cough, dyspnoea and fine bi-basal crackles. This is usually reversible and spontaneously settle within 1-3 days.

Clinical features of chronic EAA.

Finger clubbing (50%) Increasing dyspnoea Decreased weight Extertional dyspnoea Type 1 resp failure Cor pulmonale

Pathogenesis of EAA.

Chronic inflammatory infiltrates and poorly defined interstitial granulomas together with interstitial fibrosis and honeycomb change in chronic disease. Cellular immmunity and deposition of immune complexes causing foci of inflammation through activation of complement via the classical pathway.

Investigations in EAA.

Bloods - FBC (neutrophilia), raised ESR, ABGs, serum antibodies. CXR HRCT PFTs Bronchoalveolar lavage

What does serum antibodies tell you about EAA?

It does not necessarily suggest disease but purely exposure or previous sensitisation to allergen.

Findings on CXR in acute EAA.

May be normal. If abnormal you might see diffuse small nodules and increased reticular shadowing. Upper-zone mottling.

Findings on PFTs in acute EAA

These are not diagnostic. However can should reversible restrictive lung disease. Reduced gas transfer

CXR/HRCT findings in chronic EAA.

Upper-zone fibrosis Honeycomb lung. Ground glass opacities Increased reticular shadowing. In some cases, it may be difficult to differentiate from idiopathic pulmonary fibrosis - UIP cases are also thought to have honeycombing and peripheral or lower lung zone predominance of disease, and less likely to have micronodules 4.

HRCT findings on chronic EAA.

Nodules Ground glass appearance Increased reticulation Honeycomb lung Extensive fibrosis This is all usually seen in the mid or upper zones of the lungs.

What will bronchoaleolar lavage show in EAA?

Increased lymphocytes and increased mast cells.

Management of acute EAA.

Remove allergen and give O2 (35-60%) PO prednisolone 40mg/24h as a reducing course

Management of chronic EAA.

Remove allergen Wear a facemask or +ve pressure helmet. Long-term steroids often achieve CXR and physiological improvement. Azathioprine or cyclophosphamide might be used.

Causes of fibrotic shadowing on CXR in the upper zone.

TB HS pneumonitis Ankylosing spondylitis Radiotherapy Progressive massive fibrosis

Causes of fibrotic shadowing on CXR in the mid zone.

Sarcoidosis Histoplasmosis

Causes of fibrotic shadowing on CXR in the lower zone.

Idiopathic pulmonary fibrosis Asbestosis