- Epidemiology and Aetiology
- Typical presentation
- What is Interstitial lung disease?
- Idiopathic Pulmonary Fibrosis / Cryptogenic Fibrosing Alveolitis
- Extrinsic Allergic Alveolitis
- Goodpasture’s Syndrome
- Idiopathic Pulmonary Haemosiderosis
- Related Articles
- Sarcoidosis tends to occur in younger adults, and can also affect any other organ system in the body, although in 90% of cases the lungs are involved
- Sarcoidosis has a more benign prognosis and in many cases, resolves by itself
- Pulmonary fibrosis tends to occur in older adults, and causes significant morbidity and mortality
Many patients are treated with steroids, although the evidence for their benefit is not strong, and, depending on the cause – many patients (mainly those with idiopathic pulmonary fibrosis) do not respond to treatment
Epidemiology and Aetiology
- Incidence of all ILDs combined is about 30 per 100 000
- Types of interstitial lung disease
- Idiopathic pulmonary fibrosis
- Poor prognosis – median survival 3-5 years. Typically older adults
- Usually good prognosis. Can affect younger adults
- Variable prognosis depending on the cause
- Drug induced ILD
- Amiodarone, methotrexate
- Hypersensitivity ILD
- Usually has a good prognosis if the allergen is avoided
- Idiopathic pulmonary fibrosis
- Often slowly progressive
- Occasionally may mimic an acute pneumonia
- Dry cough
- Progressive shortness of breath
- May have clubbing
- May have diffuse inspiratory crackles
- Wheeze, haemoptysis and chest pain are rare
- Restrictive respiratory pattern of spirometry
- Abnormal CXR
What is Interstitial lung disease?
- Scar tissue in the lungs.
- Decreased compliance giving a RESTRICTIVE pattern in pulmonary function tests. (Fev1/FVC ratio >80%).
- End stage is “honeycomb lung”, cystic spaces develop in fibrotic lungs.
- Localised (e.g following unresolved pneumonia)
- Bilateral (e.g. in TB)
- Widespread (e.g. in idiopathic pulmonary fibrosis or pneumoconiosis)
- Dry cough
- Dyspnoea (progressive)
- Digital clubbing
- Diffuse inspiratory crackles
Idiopathic Pulmonary Fibrosis / Cryptogenic Fibrosing Alveolitis
- Reduced chest expansion
- End inspiratory crackles
- Clubbing (2/3 patients)
- FBC (raised ESR), Rh factor (+ve 50% patients), ANA (30% +ve)
- Irregular, reticulo-nodular shadows, often in lower zones, sometimes called the reticulonodular pattern
- CXR is often normal
- Usually a “high resolution CT” (HRCT)
- Ground-glass opacification
- Lung Function Tests (spirometry)
- Restrictive Pattern
- Transbronchial or open lung biopsy to confirm histological diagnosis
- Assists in defining the type of ILD that is present
The exact management plan is very individualised for the patient. Some, all or none of the below measures may be used. For idiopathic pulmonary fibrosis, no treatment has been proven to prolong survival.
- Early referral to a specialist centre for pulmonary rehabilitation is important
- Smoking cessation is extremely important for any smokers with ILDs
- A large proportion of patients do not respond well to corticosteroid treatment. High dose prednisolone for 6 weeks followed by a tapered dose is recommended in the Oxford Clinical Handbook.
- Evidence is lacking
- Treatment is often combined with azathioprine
- Combined immunosuppressive therapy can also be used including azathioprine and cyclophosphamide in conjunction with steroids.
Treat associated disorders
- Should be considered in suitable candidates
- Sarcoidosis – treatment only indicated if disease is progressive and / or has significant symptoms
- Prednisolone – 0.5mg/Kg/day is usually the recommended treatment, for one month, and then weaning to the lowest effective dose, reviewed every 6-12 months
- Connective tissues diseases – treat the underling disorder. Often a similar prednisolone regimen to that recommended for sarcoidosis
- Hypersensitivity pneumonitis – avoidance of the antigen is the primary treatment. Prednisolone may be used if there is severe or progressive disease
Pneumoconiosis is covered in more detail in its own article.
Coal worker’s Pneumoconiosis
- Simple Pneumoconiosis– Usually asymptomatic, but can have co-existent bronchitis. Diagnosis is made from CXR on finding small, round opacities in the upper zones. Avoidance of exposure to further dust can stop it from progressing. Patients are entitled to claim compensation via the Industrial Injuries Act.
- Progressive Massive Fibrosis– Can occur on top of simple CWP. Large, round fibrotic nodules >10mm seen on CXR, usually upper zones. Nodules can become infected by tuberculosis. The associated emphysema is severe. Cough, dyspnoea and production of black sputum may be present (sputum black due to ruptured, cavitating lesions, hence the name “the black lung”). This can progress despite cessation of exposure to dust, there is no specific treatment. Patients will eventually develop pulmonary hypertension and cor pulmonale.
Extrinsic Allergic Alveolitis
- Mouldy hay (Farmer’s lung)
- Bird Faeces (bird fancier/pigeon fancier’s lung)
- Cotton fibres (bysinossis)
- Sugar cane fibres (bagassosis)
Idiopathic Pulmonary Haemosiderosis
- Interstitial lung disease - a diagnostic approach - RACGP
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy