Interstitial Lung Disease, Respiratory Bronchiolitis-Associated

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

Age 40–45 years

Insidious dry cough with exertional dyspnea over months to years

Diffuse parenchymal infiltrates

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

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