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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
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Chest radiographic findings
High-resolution CT scan shows minimal ground-glass and variable honeycombing changes
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
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