Interstitial Lung Disease, Respiratory Bronchiolitis-Associated

Key Features

• Presentation similar to usual interstitial pneumonitis (UIP) but occurs in younger patients

• Patients are invariably heavy smokers

• Usually occurs without symptoms or physiologic evidence of lung disease

• Prognosis is better than in UIP; median survival > 10 years

Clinical Findings

• Age 40–45 years

• Insidious dry cough with exertional dyspnea over months to years

• Diffuse parenchymal infiltrates

Diagnosis

• Pulmonary function test shows restriction with decreased DL_CO, usually less severe than that seen in UIP

• High-resolution CT more likely to reveal diffuse ground-glass opacities and upper lobe emphysema

• Biopsy shows increased numbers of macrophages localized within the peribronchiolar space; alveolar architecture is preserved, honeycomb change and fibrosis are minimal

Treatment

• Spontaneous remission occurs in up to 20% of patients

• Smoking cessation is crucial

• Trial of prednisone, 1–2 mg/kg/day orally for a minimum of 2 months