Disorder | Clinical features | HRCT | Histopathology |
Bronchiolitis obliterans (also called constrictive bronchiolitis/obliterative bronchiolitis) | Dyspnea, cough; PFTs normal or show airflow limitation without bronchodilator reversibility; predisposing process (eg, inhalational or drug exposure, rheumatic disease, lung or hematopoietic transplant) | - Mosaic attenuation
- Air trapping seen on inspiratory and expiratory views
- Bronchial wall-thickening (eg, "v" or "y" shaped branching linear opacities)
- Centrilobular nodules
| - Constrictive bronchiolitis: concentric narrowing or complete obliteration of airway lumen
- Bronchiolar hypertrophy
- Bronchiolectasis
- Few lymphocytes
|
Proliferative bronchiolitis (organizing pneumonia) | Usually seen in the context of cryptogenic or secondary organizing pneumonia or nitrogen dioxide exposure | - Peripheral, patchy air-space consolidation or ground-glass opacities, small nodular opacities, and bronchial wall thickening with dilation
| - Fibroblast proliferation and an organizing, polypoid intraluminal exudate in respiratory bronchioles and alveolar ducts
- Foamy macrophages in alveoli
|
Follicular bronchiolitis | Progressive dyspnea; associated with rheumatic diseases, immunodeficiency, hypersensitivity pneumonitis | - Centrilobular nodules; may have patchy ground glass opacity
| - Lymphoid hyperplasia of bronchus-associated lymphoid tissue; germinal centers
|
Respiratory bronchiolitis | Almost exclusively in smokers; asymptomatic finding on biopsy performed for another reason | - Ill-defined centrilobular nodules
- Patchy ground-glass opacities
- Air-trapping
- "Tree-in-bud" opacities
| - Mild bronchiolar inflammation, tan-pigmented macrophages within the lumens of first and second order respiratory bronchioles
- Tan-pigmented macrophages in the respiratory bronchioles
- Patchy submucosal and peribronchiolar infiltrate of lymphocytes and histiocytes
|
Airway-centered interstitial fibrosis | Chronic nonproductive cough; usually seen in smokers; PFTs restrictive or obstructive; percentage of lymphocytes on bronchoalveolar lavage is less than 40% | - Peribronchovascular ground glass opacities, traction bronchiectasis, and thickening of bronchial walls
| - Centrilobular and bronchiolocentric inflammatory infiltrate with peribronchiolar fibrosis and an absence of granulomas
|
Diffuse panbronchiolitis | History of sinusitis (75%) and productive cough; generally limited to patients in Japan | - Centrilobular nodules
- "Tree-in-bud" opacities
- Thickened and dilated bronchiolar walls (bronchiolectasis)
- Large cystic opacities are a late finding
| - Bronchiolar transmural infiltrate composed of lymphocytes, plasma cells, and distinctive lipid-laden "foamy" macrophages
|