Idiopathic Pulmonary Fibrosis

Progressive interstitial fibrosis of unknown cause

Aetiology

  • Most common in smokers and older people
  • Exact cause unknown

Pathophysiology

  • Repetitive injury to the alveolar epithelium, caused by currently unidentified environmental stimuli, leads to the activation of repair pathways
  • The the wound healing mechanisms become uncontrolled, leading to subpleural and basal fibrosis
  • Terminally, lung structure is replaced by dilated spaces surrounded by fibrous walls - ‘honeycomb’

Clinical presentation

Symptoms

  • Progressive dyspnoea
  • Dry cough
  • Weight loss
  • Fatigue
  • Malaise

Signs

  • Clubbing
  • Cyanosis
  • Bilateral fine inspiratory crackles

Investigations

CXR

  • Bilateral basilar/lower zone reticulonodular shadows
  • Bilateral infiltrates
  • Reduced lung volume

CT scan

  • Basal and sub-pleural reticulonodular shadowing
  • Ground glass appearance (early phase change)
  • Honeycombing (late phase change)

PFTs

  • Restrictive pattern

Lung biopsy

  • Not necessary if CT scan is diagnostic
  • Usual interstitial pneumonia (UIP) is the histological finding seen in IFP - increased number of chronic inflammatory cells

Management

  • Antifibrotic drugs (nintedanib, pirfenidone) - slow progression
  • Oxygen if hypoxic
  • Lung transplant in young patients