Interstitial lung disease

Differential Diagnosis

• Primary
  • IPF
  • COP
  • NSIP
• Secondary
  • Inflammatory or connective tissue diseases
    • Rheumatoid arthritis
    • Systemic lupus erythematosus
    • Dermatomyositis
    • Systemic sclerosis
    • Sarcoidosis
  • Exposures
    • Hypersensitivity pneumonitis
    • Drugs: nitrofurantoin, chemotherapy (cyclophosphamide, bleomycin), methotrexate, amiodarone
    • Inorganic exposures: silicosis and asbestosis
    • Occupational and hobby exposures
      • Hypersensitivity pneumonitis, including bird fancier's lung, cheese-washer's lung, farmer's lung
      • Hot tub lung (Mycobacterium avium)
    • Radiation pneumonitis
• Mimickers
  • Congestive heart failure
  • Interstitial infections
    • Pneumocystis jirovecii pneumonia
    • Mycoplasma
    • Legionella
    • Viral pneumonia
  • Lymphangitic carcinomatosis

By Location Predominance

Upper Lobe Predominance (HASTEN)

• Hypersensitivity pneumonitis
• Ankylosing spondylitis
• Sarcoidosis and silicosis
• Tuberculosis, viral pneumonia, Mycoplasma
• Eosinophilic granulomas (aka pulmonary Langerhan cell histiocytosis, present with spontaneous pneumothorax)
• Neurofibromatosis

Lower Lobe Predominance (BAD RASH)

• Bleomycin
• Amiodarone
• Drugs: nitrofurantoin, cyclophosphamide, methotrexate
• Rheumatoid lung
• Asbestosis
• Scleroderma
• Hamman-Rich syndrome (aka acute interstitial pneumonia = rare, fulminant form of IPF)