Interstitial Lung Disease



  • Progressive SOB on exertion
  • Dry cough
  • Malaise, fatigue
  • Weight loss


On examination:


  • Clubbing
  • Scars
  • Reduced chest expansion
  • Fine late end-inspiratory crepitations that do not clear with coughing but do quieten/disappear on leaning forwards


Comment on whether there is evidence of complications such as respiratory failure (oxygen, cyanosis, CO2 retention flap) or cor pulmonale (RV heave, loud P2, raised JVP, peripheral oedema) or infection (bronchial breathing, antibiotics at bedside, fever)


Tell the examiner that you suspect interstitial lung disease affecting the upper/lower zones.

Comment on whether there are signs of a possible underlying cause:

  • Rheumatoid arthritis: peripheral symmetrical deforming polyarthropathy (swan neck deformity, Z thumb, ulnar deviation at wrist, may have nodules) NB: the cause of the pulmonary fibrosis may be RA itself or methotrexate use in an RA patient
  • Amiodarone: slate grey appearance, pacemaker, may be in AF, photosensitivity
  • Connective tissue disease: cutaneous signs of systemic sclerosis, lupus, dermatomyositis (See “station 5” section on website)
  • Ankylosing spondylitis: question mark posture, protuberant abdomen (See “station 5 Ankylosing Spondylitis”)
  • Radiation: may have radiation tattoo on chest wall, lymphadenopathy
  • Sarcoidosis: cutaneous signs of sarcoidosis (See “Station 5 Sarcoidosis”)


Comment on whether there are signs of treatment:


  • Steroid usage: Cushingoid, thin skin, bruising, proximal myopathy
  • Oxygen
  • Ciclosporin: gum hypertrophy
  • Scars- eg. from lung transplant


Comment that your differential diagnosis for clubbing and crepitations includes:


  1. NB: in bronchiectasis crepitations are early, coarse and change with coughing and there may be extra clues such as sputum pot at the bedside
  2. Lung Cancer: cachexia, tar staining, lymphadenopathy
  3. Abscess
  4. Cystic fibrosis


Other causes of crepitations include:


  • Pneumonia
  • Heart Failure


Classification of interstitial lung disease:


Diffuse parenchymal lung disease of known cause:


  1. Collagen vascular disease: RA, SLE, dermato/polymyositis, systemic sclerosis, ankylosing spondylitis, Sjogrens syndrome, mixed connective tissue disease
  2. Occupational/environmental: pneumoconiosis (asbestosis, silicosis, berylliosis, byssinosis, coal etc), extringic allergic alveolitis (farmers lung, bird fanciers lung etc), chemical inhalation (mercury, lead etc)
  3. Drug-related: amiodarone, methotrexate, bleomycin, phenytoin, nitrofurantoin, gold, sulphasalasine, isoniazid, cyclophosphamide, busulphan, carbamazepine, radiation etc.
  4. Post-infection: TB, fungal, viral, ABPA
  5. Smoking
  6. Other systemic disorders: sarcoidosis, vasculitis, IBD, renal tubular acidosis, hep C, thyroid, neurofibromatosis, tuberous sclerosis


There are also idiopathic interstitial pneumonias:


  1. Idiopathic pulmonary fibrosis (Usual interstitial pneumonia on histology)
  2. NSIP (non-specific interstitial pneumonia)
  3. COP (cryptogenic organising pneumonia)
  4. LIP (lymphocytic interstitial pneumonia)
  5. AIP (acute interstitial pneumonia)
  6. RBILD (respiratory bronchiolitis-associated interstitial lung disease)


Symmetrical causes:


Upper Zone Fibrosis (BREAST)



Radiation e.g. for breast cancer

Extringic allergic alveolitis, pneumoconiosis e.g. coal workers

Ankylosing spondylitis, ABPA (Allergic bronchopulmonary aspergillosis)

Silicosis, sarcoidosis psoriasis

Tuberculosis (and histoplasmosis and histiocytosis-X)


Lower Zone Fibrosis (RASIO)


Rheumatoid arthritis


Scleroderma, SLE, Sjogrens (and poly/dermatomyositis)

Idiopathic pulmonary fibrosis

Others: Drugs- methotrexate, bleomycin, busulphan, cyclophosphamide, nitrofurantoin, isoniazid, amiodarone, phenytoin, carbamazepine, gold, sulphasalasine.


Asymmetrical causes: TB or malignancy





Bedside tests:

ABG (respiratory failure)

ECG (right heart strain)


Laboratory tests:

Bloods: FBC (eosinophilia, anaemia, polycythaemia), CRP, ESR, Immunoglobulins, complement, autoimmune screen (ANA, ANCA, RF, anti-CCP, CK, anti-GBM etc.), serum precipitins (hypersensitivity pneumonitis), serum ACE (sarcoidosis)


CXR to diagnose, assess extent and distribution, complications and cause e.g. bihilar lymphadenopathy may suggest sarcoidosis, pleural plaques may be seen if asbestosis, and exclude differentials

  • Bilateral reticulonodular interstitial infiltrates (parenchymal shadowing)
  • Ground-glass/honeycombing if advanced
  • Volume loss

HRCT to diagnose, assess extent and distribution and severity, complications and cause and pattern, and exclude differentials.  Much more sensitive than CXR (detects disease even if CXR normal). This is the diagnostic test of choice.

  • Reticulation
  • Ground glass (usually good response to steroid treatment)
  • Volume loss
  • Honeycombing


Special tests:

Lung function tests: Restrictive pattern with reduced transfer factor

BAL (cell type eg. eosinophils/neutrophils/lymphocytes, malignant cells, asbestos bodies etc.)

Video assisted, open or transbronchial biopsy if no clear diagnosis to look at histology

Echo: to assess for pulmonary hypertension





Stop smoking, remove causative allergen/medication, vaccines (influenza, pneumococcal), claim compensation (asbestos), pulmonary rehab


Treat the underlying cause

Manage complications e.g. infective exacerbations, pulmonary hypertension and cor pulmonale, lung cancer, respiratory failure


Immunosuppressants e.g. azathioprine, cyclophosphamide

Antioxidants e.g. N acetylcysteine

Pirfenidone (antifibrotic  and anti-inflammatory agent)


Single/double lung transplant




Written by Dr Sarah Kennedy


Resources used to make this document include the references listed on the PACES webpage