BRONCHIOLITIS OBLITERANS

A fibrotic lung disease that primarily affects the small conducting airways and spares most of the interstitium.

1.     Pathology: epithelial injury with a repair process causing an excessive proliferation of granulation tissue which compromises or completely obliterates the airway lumen.

2.     Physiology: obstructive or restrictive ventilatory defect.

3.     CXR: airspace and/or interstitial changes.

Bronchiolitis obliterans of known etiology

1.     Toxic Fume Inhalation (S0₂, N0₂, NH₃)

a.      Steroids occasionally helpful.

2.     Postinfectious Bronchiolitis Obliterans

a.      RSV most common cause in infants and young children.

b.     Mycoplasma, legionella and several viruses most common cause in adults.

Bronchiolitis obliterans of unknown etiology

1.     Bronchiolitis Obliterans and Organizing Pneumonia

a.      Also known as BOOP.

b.     Steroids effective.

2.     Connective Tissue Disease

a.      Rheumatoid arthritis, systemic lupus, polymyositis and dermatomyositis, Sjogren's syndrome.

3.     Organ Transplantation

a.      Bone marrow transplantation
- May occur in 10% of long-term survivors.

b.     Heart/Lung transplantation
- May occur in 30-50% of long-term survivors.

4.     Associated with other disease

a.      IPF

b.     Hypersensitivity pneumonitis

c.      Eosinophilc granuloma

d.     Chronic eosinophilic pneumonia.