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For further information, see CMDT Part 9-21: Diffuse Interstitial Pneumonias

Key Features

  • Clinical presentation is similar to that of other idiopathic interstitial pneumonias

  • Median survival is approximately 3 years

Clinical Findings

  • Onset at age 55–60 with slight male predominance

  • Presents as insidious dry cough with months to years of exertional dyspnea

  • Clubbing is present at diagnosis in 25–50%

  • Pulmonary function tests: restrictive pattern and decreased diffusion capacity

  • Antinuclear antibodies (ANA) and rheumatoid factor (RF) are positive in 25% of patients without documented collagen vascular disease


  • High-resolution CT scan

    • Shows increased linear or reticular bibasilar and subpleural opacities, with associated honeycombing

    • Unilateral disease is rare

    • Minimal ground-glass opacities

    • Areas of normal lung may be adjacent to areas of advanced fibrosis

  • Biopsy shows nonuniform distribution of fibrosis, with loss of type I pneumocytes and proliferation of alveolar type II cells

  • Usual interstitial pneumonia can be diagnosed with 90% confidence in patients age > 65 with classic features, avoiding biopsy


  • Nintedanib and pirfenidone appear to reduce rate of decline in lung function and have received FDA approval for usual interstitial pneumonia

  • Refer early for lung transplantation evaluation

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