Interstitial Lung Disease

Question 1

Interstitial Lung Disease

Answer 1

Interstitial lung disease= a collective term for a group of conditions that cause inflammationandfibrosisofthelungparenchyma/tissue. Fibrosisinvolves the replacement of elastic and functional lung tissue with non-functional scar tissue.

Such conditions include:
- Idiopathic pulmonary fibrosis (the most important to remember)
- Secondary pulmonary fibrosis
- Hypersensitivity pneumonitis
- Cryptogenic organising pneumonia
- Asbestosis

Question 1

Interstitial Lung Disease: Symptoms

Answer 1

• Dysponea on exertion
• Dry cough
• Fatigue

Question 2

Interstsitial Lung Disease: Examinations Signs

Answer 2

Patients withidiopathic pulmonary fibrosishave typical findings on examination:

• Bibasal fine end-inspiratory crackles
• Finger clubbing

Question 3

Interstitial Lung Disease: Diagnosis

Answer 3

• Clinical features
• High-resolution CT scan (HRCT) of the thorax (showing a typical “ground glass” appearance)
• Spirometry – normal or restrivtive pattern (equal reduction in FEV1:FVC but ratio >70%)

Other investigations where there is doubt about the diagnosis include:
- Lung biopsy
- Bronchoalveolar lavage - Raised lymphocytes(lymphocytosis) are suggestive of hypersensitivity pneumonitis.

Question 4

Interstitial Lung Disease: Management

Answer 4

poor prognosis and limited management options in interstitial lung disease, and treatment is primarily supportive. Options include:

• Remove or treat the underlying cause
• Home oxygen where there is hypoxia
• Stop smoking
• Physiotherapy and pulmonary rehabilitation
• Pneumococcal and flu vaccine
• Advanced care planningand palliative care where appropriate
• Lung transplant is an option, but the risks and benefits need careful consideration

Two medications are licensed that can slow the progression of the disease:
- Pirfenidonereduces fibrosis and inflammation through various mechanisms
- Nintedanibreduces fibrosis and inflammation by inhibitingtyrosine kinase

Question 5

Interstitial Lung Disease: Aetiology

Answer 5

Secondary Pulmonary Fibrosis

Several drugs can cause pulmonary fibrosis:

• Amiodarone (also causes grey/blue skin)
• Cyclophosphamide
• Methotrexate
• Nitrofurantoin

Pulmonary fibrosis can occur secondary to other conditions:

• Alpha-1 antitrypsin deficiency
• Rheumatoid arthritis
• Systemic lupus erythematosus (SLE)
• Systemic sclerosis
• Sarcoidosis

Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis, also calledextrinsic allergic alveolitis, involvestype IIIandtype IV hypersensitivity reactionto an environmental allergen. Inhalation of allergens in patients sensitised to that allergen causes an immune response, leading to inflammation and damage to the lung tissue.

Bronchoalveolar lavageis performed during a bronchoscopy procedure. The airways are washed with sterile saline to gather cells, after which the fluid is collected and analysed.Raised lymphocytes(lymphocytosis) are suggestive of hypersensitivity pneumonitis.

Management involves removing the allergen, oxygen where necessary and steroids.

Examples of specific causes:

• Bird-fancier’s lungis a reaction to bird droppings
• Farmer’s lungis a reaction to mouldy spores in hay
• Mushroom worker’s lungis a reaction to specific mushroom antigens
• Malt worker’s lungis a reaction to mould on barley

Cryptogenic Organising Pneumonia

Cryptogenic organising pneumonia was previously known asbronchiolitis obliterans organising pneumonia. It involves a focal area of inflammation of the lung tissue. It can be idiopathic or triggered by infection, inflammatory disorders, medications, radiation, environmental toxins, or allergens.

Presentation is similar to infectious pneumonia, with shortness of breath, cough, fever and lethargy. Inspiratory crackles may be heard on auscultation.

Chest x-rayfindings are also similar to pneumonia, with a focal consolidation. Alung biopsyis the definitive investigation. Diagnosis is often delayed due to the similarities to infectious pneumonia.

Treatment is withsystemic corticosteroids.

Asbestosis
Asbestosis refers tolung fibrosisrelated to asbestos exposure. Asbestos isfibrogenic, meaning it causes lung fibrosis. It is alsooncogenic, meaning it causes cancer. The effects of asbestos usually take several decades to develop. Asbestos inhalation causes several problems:

• Lung fibrosis
• Pleural thickening and pleural plaques
• Adenocarcinoma
• Mesothelioma

Patients may be eligible for compensation if they develop asbestos-related health conditions. All deceased patients with occupational asbestos exposure must be referred to the coroner.