Makindo Medical Notes

🫁 Diffuse Parenchymal Lung Disease (DPLD), also called Interstitial Lung Disease (ILD), refers to a group of >200 conditions causing inflammation and fibrosis of the pulmonary interstitium and alveoli. The result is progressive breathlessness, reduced gas exchange, and eventual respiratory failure.

📖 About

• Over 200 causes; many idiopathic or poorly understood.
• Fibrosis disrupts gas transfer at the alveolar–capillary membrane.
• Some cases are reversible (e.g. hypersensitivity pneumonitis), but many are progressive (e.g. IPF).

🧬 Aetiology & Risk Factors

• Genetic: MUC5B variant → associated with milder IPF.
• Environmental: smoking 🚬, dusts, asbestos, silica, coal.
• Drugs: methotrexate, bleomycin, amiodarone, nitrofurantoin, statins.
• Radiation therapy.

🔑 Key Types

• Idiopathic pulmonary fibrosis (IPF)
• Sarcoidosis (non-caseating granulomas)
• Connective tissue disease–associated ILD (RA, Scleroderma, Polymyositis, Dermatomyositis, SLE, IBD)
• Hypersensitivity pneumonitis
  • Farmer’s lung 🌾 (mouldy hay)
  • Bird fancier’s lung 🐦 (avian proteins)
• Cryptogenic organising pneumonia
• Pneumoconiosis
  • Asbestosis
  • Silicosis
  • Coal workers’ pneumoconiosis

🩺 Clinical Features

• Progressive exertional dyspnoea & dry cough.
• Reduced chest expansion, fine “Velcro” crackles at lung bases.
• Weight loss, fatigue, eventual hypoxaemia.
• Clubbing → esp. IPF & asbestosis.
• Extra-pulmonary clues: rash, synovitis, erythema nodosum, Raynaud’s.
• Haemoptysis, chest pain, purulent sputum are unusual → think alternative diagnosis.

🔬 Investigations

• Bloods: FBC, U&E, CRP/ESR, autoantibody panel (ANA, ENA, RF, anti-CCP, anti-Jo1, SCL-70), ACE (sarcoid).
• CXR: Reticular “net-like” opacities.
• HRCT: Gold standard → ground glass, reticulation, honeycombing, traction bronchiectasis, subpleural fibrosis.
• Spirometry: Restrictive picture – ↓FVC, ↓FEV1 (ratio preserved), ↓DLCO.
• BNP: if pulmonary hypertension/CCF suspected.
• Lung biopsy: (surgical or transbronchial) – may show Usual Interstitial Pneumonia (UIP) in IPF.
• Allergen testing: RAST if hypersensitivity suspected.

🧾 Differential Diagnosis

• Bronchiectasis
• Heart failure (can mimic on CXR/echo)

🔬 Pathology & Distribution

• Honeycomb lung = end-stage fibrosis.
• Granulomas = sarcoidosis, HP, TB.
• Upper lobe → “SCHART” mnemonic: Silicosis, Sarcoid, Coal workers, Histiocytosis, Ankylosing spondylitis, Radiation, TB.
• Lower lobe → “RASIO” mnemonic: RA, Asbestosis, Scleroderma, IPF, Other drugs.

💊 Management

• Supportive: Oxygen therapy, pulmonary rehabilitation, vaccination.
• IPF: Antifibrotics (Pirfenidone, Nintedanib) – slow decline but do not reverse disease.
• Sarcoidosis: Steroids ± methotrexate/azathioprine.
• CTD-associated ILD: Immunosuppressants (steroids, mycophenolate, cyclophosphamide).
• Hypersensitivity pneumonitis: Antigen avoidance + steroids.
• Lung transplantation for end-stage disease.

📚 References

• Diffuse Parenchymal Lung Disease – ERS Review
• NICE NG163: IPF Antifibrotic Therapy