Clinical Review

How to investigate a patient with suspected interstitial lung disease

BMJ 2010; 340 doi: (Published 09 June 2010) Cite this as: BMJ 2010;340:c2843
  1. Owen J Dempsey, consultant chest physician1,
  2. Keith M Kerr, professor of pulmonary pathology2,
  3. Hardy Remmen, consultant cardiothoracic surgeon3,
  4. Alan R Denison, clinical senior lecturer and honorary consultant thoracic radiologist4
  1. 1Department of Respiratory Medicine, Aberdeen Royal Infirmary, Foresterhill, Aberdeen AB25 2ZN
  2. 2Aberdeen University Medical School, Foresterhill, Aberdeen AB25 2ZD
  3. 3Department of Cardiothoracic Surgery, Aberdeen Royal Infirmary
  4. 4Aberdeen Biomedical Imaging Centre, Aberdeen Royal Infirmary
  1. Correspondence to: O J Dempsey owen.dempsey{at}

    Patients with interstitial lung disease often present with breathlessness, chronic cough, inspiratory crackles on auscultation, and abnormal spirometry.1 2 Over 200 different types of disease can cause thickening of the pulmonary interstitium, with the common final pathway for many of these being fibrosis (figs 1 and 2) .3 4 Some forms of interstitial lung disease can be life threatening, such as idiopathic pulmonary fibrosis, approximately 4000 new cases of which are diagnosed in England and Wales each year. Survival rates of 57% at three years and 43% at five years are worse outcomes than those for some cancers.5 About 3000 new cases of sarcoidosis are diagnosed each year in the UK.5 6

    Early recognition and treatment of interstitial lung diseases may prevent progression to irreversible pulmonary fibrosis and respiratory failure. This review provides a guide to the initial investigation of patients with suspected interstitial lung disease and provides a summary of further investigations.

    Fig 1 The pulmonary interstitium is the microscopic space between the alveolar epithelium and capillary endothelium and is crucial for gas exchange

    Fig 2 Arrows indicate pulmonary interstitium in (left) healthy lung and (right) pulmonary fibrosis. The grossly thickened interstitium in pulmonary fibrosis impairs gas exchange.

    Sources and selection criteria

    We sought papers that were fully published between 1966 and April 2010 using appropriate index terms (interstitial lung disease, diffuse parenchymal lung disease) the National Library of Medicine’s computerised search service (providing access to Medline, PreMedline and other related databases). We also consulted Cochrane database systematic reviews and a personal archive of references.

    What are the most common interstitial lung diseases and how are they classified?

    Some forms of interstitial lung disease are idiopathic, whereas others are associated with connective tissue diseases, commonly prescribed drugs, smoking, and exposures to environmental factors such as dusts.7 The histopathological classification of interstitial lung diseases is complex, simplified in figure 3 …

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