oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.
Pulmonary fibrosis describes a group of diseases which produce interstitial lung damage and ultimately fibrosis and loss of the elasticity of the lungs. It is a chronic condition characterised by shortness of breath, diffuse infiltrates on CXR and inflammation and/or fibrosis on biopsy. Pulmonary fibrosis may be secondary to a wide range of diseases or may be idiopathic with no known underlying cause. There are three types of lung fibrosis:
- Replacement fibrosis secondary to lung damage - eg, infarction, tuberculosis and pneumonia.
- Focal fibrosis in response to irritants - eg, coal dust and silica.
- Diffuse parenchymal lung disease (DPLD), which occurs in fibrosing alveolitis (idiopathic pulmonary fibrosis (IPF)) and extrinsic allergic alveolitis.
See separate article Idiopathic Pulmonary Fibrosis for more details on this condition.
Pulmonary fibrosis is present worldwide, and is represented equally in all ethnic groups.
- Estmated incidences of idiopathic pulmonary fibrosis (IPF) of between 6.8-16.3 per 100,000 person-years have been estimated and the incidence was noted to be increasing in a UK study between 1991 and 2003 by more than 10%. Interestingly, this increase in incidence does not appear to relate to increasing age or improvement in diagnosis rates.
- The incidence of other forms depends on the degree of exposure to causative agents and therefore varies worldwide.
- Many causes of pulmonary fibrosis develop over many years and are therefore often seen in older adults.
- The peak age of incidence is 50-70 years and males and females appear to be equally affected.
- However, some forms of interstitial lung disease - eg, sarcoidosis, connective tissue diseases and inherited forms of lung disease - usually present in younger adults.
- Some forms of pulmonary fibrosis are caused by drugs and environmental causes, including occupational.
- Some forms of diffuse pulmonary fibrosis are mainly seen in current smokers or ex-smokers.
- Gastro-oesophageal reflux disease.
- Infectious agents.
- Genetic factors.
IPF is the most common cause of interstitial lung disease. There are many known causes of pulmonary fibrosis:
- Replacement fibrosis secondary to lung damage - eg infarction, tuberculosis and pneumonia.
- Pneumoconioses - eg, silicosis, asbestosis, berylliosis, coal worker's pneumoconiosis.
- Extrinsic allergic alveolitis - eg, farmer's lung, bird fancier's lung, mushroom worker's lung, cheese worker's lung, etc.
- Exposure to toxic gases, fumes, aerosols, and vapours - eg, silo filler's disease (lung exposure to oxides of nitrogen).
- Granulomatous diseases - eg, sarcoidosis.
- Exposure to drugs - eg, amiodarone, bleomycin, busulfan, nitrofurantoin, methotrexate, gold, penicillamine, and also illicit drugs - eg, crack cocaine, heroin.
- Radiation exposure.
- Connective tissue diseases - eg, scleroderma, systemic lupus erythematosus, rheumatoid arthritis, mixed connective tissue disease.
- Other systemic illnesses, including hepatitis C, inflammatory bowel disease, acquired immunodeficiency syndrome.
- Inherited causes - eg, familial IPF, tuberous sclerosis, neurofibromatosis, Niemann-Pick disease, Gaucher's disease, Hermansky-Pudlak syndrome (a type of albinism).
- The presentation is variable and related to the underlying disease process.
- The presentation may be:
- Acute, with a fulminant, progressive, remitting, or resolving course.
- Subacute, with a resolving, remitting, relapsing, or progressive course.
- Chronic, insidious, and slowly progressive.
- Most patients with IPF present with a gradual onset of dyspnoea and/or a nonproductive cough.
- Diagnosis may be made by the incidental findings on CXR, spirometry, or as a result of screening for high-risk occupational exposure, such as asbestos.
- The main symptoms include dyspnoea, chronic cough, wheezing, haemoptysis and chest pain.
- Examination findings may include central cyanosis, fine end-inspiratory pulmonary crackles.
- Nonspecific features may include low-grade fever and myalgia.
- Finger clubbing is common with some causes of pulmonary fibrosis, especially with advanced disease - eg, idiopathic pulmonary disease and asbestosis.
- Signs of pulmonary hypertension and right heart failure occur late in the disease.
Numerous other chest diseases can give rise to some of the symptoms and signs of pulmonary fibrosis and other forms of alveolar inflammation may also give a similar histological pattern. Other diseases which may mimic pulmonary fibrosis include:
- Chronic obstructive pulmonary disease.
- Congestive heart failure.
- Atypical pneumonia (including Pneumocystis jirovecii).
- Lung cancer.
A detailed history is essential, especially with respect to occupational history, to rule out exposure to asbestos, silica and other respirable toxins as a cause for the underlying symptoms.
- FBC may show mild anaemia.
- ESR and/or CRP may be raised.
- Autoantibodies including antinuclear antibodies, rheumatoid factor.
- Arterial blood gases: oxygen desaturation is common.
- Lung function tests may be used to aid diagnosis and to follow disease progress. They show:
- Restrictive pattern (but obstruction of airways may also be present).
- Reduced total lung capacity.
- Reduced residual capacity.
- Reduced residual volume.
- Reduced gas transfer.
- This may show no abnormality.
- Reticular and/or nodular opacities.
- Honeycombing is a late finding and correlates with severe disease.
- High-resolution chest CT scanning is more sensitive than chest radiography and may reveal characteristic findings. It may be used to assess the extent of the disease and to follow progress.
- Bronchoalveolar lavage has been used as a research tool in IPF but the role in clinical diagnosis is limited.
- Patients may require open or thoracoscopic lung biopsy to establish a definitive diagnosis. Lung biopsy is not mandatory when there are characteristic high-resolution CT scan findings or confirmed diagnosis of an underlying disease.
Treatment of the underlying cause when applicable.
General supportive measures
- Smoking cessation.
- Avoidance of any other environmental (including occupational) causes.
- Stopping any medication thought to be causing or contributing to pulmonary fibrosis.
- Patients should be encouraged to receive influenza vaccination and pneumococcal vaccine.
- Oxygen therapy may be useful for any patients who demonstrate significant hypoxaemia.
- Pulmonary rehabilitation may improve exercise tolerance and quality of life.
- Immunosuppressive therapy - eg, corticosteroids and/or cytotoxic drugs (most commonly, azathioprine) may be indicated.
- Other immunosuppressive or antifibrotic agents, such as colchicine, ciclosporin, and D-penicillamine, have been researched and may have a role to play.
- Lung transplantation may be a treatment option for selected patients.
These include pulmonary hypertension, coronary artery disease and lung cancer.
- The prognosis is variable and depends on the specific diagnosis and severity. Some diseases are insidious in onset and with gradual progression, while other diseases are acute in onset but responsive to therapy.
- Poor outcome is associated with:
- Older age.
- Male gender.
- Severe dyspnoea.
- History of cigarette smoking.
- Severe loss of lung function.
- Appearance and severity of fibrosis on radiological studies.
- Lack of response to therapy.
- Prominent fibroblastic foci on histopathological evaluation.
Further reading & references
- Pulmonary Fibrosis Foundation
- Orens JB, Estenne M, Arcasoy S, et al; International guidelines for the selection of lung transplant candidates: 2006 update--a consensus report from the Pulmonary Scientific Council of the International Society for Heart and Lung Transplantation. J Heart Lung Transplant. 2006 Jul;25(7):745-55.
- Summerhill EM, Interstitial (Nonidiopathic) Pulmonary Fibrosis, Medscape, Jun 2011
- Idiopathic Pulmonary Fibrosis: Evidence-based Guidelines for Diagnosis and Management, European Respiratory Society and others (2011)
- Mallick S; Outcome of patients with idiopathic pulmonary fibrosis (IPF) ventilated in Respir Med. 2008 Oct;102(10):1355-9. Epub 2008 Jul 17.
- Godfrey A et al, Idiopathic Pulmonary Fibrosis, Medscape, Jul 2012
- Zisman DA, Keane MP, Belperio JA, et al; Pulmonary fibrosis. Methods Mol Med. 2005;117:3-44.
Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.
Dr Hayley Willacy
Dr Gurvinder Rull
Prof Cathy Jackson