Idiopathic Pulmonary Fibrosis (IPF)

• Diffuse parenchyma lung diseases (DPLD) – heterogeneous group of conditions affected the pulmonary parenchyma/interstitium
  • Often present with progressive dry cough and breathlessness
• IPF is defined as a progressive fibrosing interstitial pneumonia of unknown cause

Epidemiology/Etiology

• IPF is the most common IIPs (idiopathic interstitial pneumonias)
• Onset is MC in 60s
• MC in men
• Etiology unknown
  • Risk factors – cigarettes, metal/wood/coal dust, silica, mold spores, EBV, methotrexate, chronic GERD

Pathogenesis

• Repetitive injury to alveolar epithelium due to an unknown stimuli
• Leads to uncontrolled wound healing mechanisms
  • Overproduction of fibroblasts
  • ↑deposition of extracellular matrix in the interstitium
• Structural integrity of lung parenchyma is disrupted
  • Loss of elasticity
  • Impaired gas exchange

Pathology

• Heterogenous appearance – areas of normal lung punctuated by areas of marked fibrosis
  • Honeycomb cysts –enlarged air spaces with thick fibrotic walls (often filled with mucin and inflammatory cells)
    • MC in subpleural areas

Clinical features

• Insidious onset of progressive dyspnoea accompanied by dry cough ± sputum
• Finger clubbing
• Crackles
• Weight loss
• Fatigue
• Overtime disease can progress to cause pulmonary hypertension, cor pulmonale, type 1 respiratory failure

Diagnosis

• Respiratory function tests – show restrictive pattern
  • FEV/FVC >70%
• Blood tests – ANA , RF
• CXR – ↑reticular shadowing, ground glass appearance
• CT – imaging of choice. Shows characteristic abnormalities
  • Basal distribution
  • Subpleural reticulation
  • Traction bronchiectasis
  • Honeycombing

Treatment

• Poor prognosis – median survival time is 2-5 years
• Smoking cessation
• Treat underlying GERD
• Immunosuppression – corticosteroids, azathioprine, cyclophosphamide
• Pirfenidone – antifibrotic agent
• Lung transplant