Cryptogenic Organizing Pneumonia - Bronchiolitis Obliterans Organizing Pneumonia
Definition
- Subacute onset lung disease characterized by intra-air space plugs of granulation tissue
Alternate/Historical Names
- BOOP
Diagnostic Criteria
- Organizing pneumonia (BOOP) is a pattern that has many causes including
- Infection, toxins, drugs, radiation, inflammatory bowel disease
- May present associated with connective tissue disease
- When idiopathic, it is termed cryptogenic organizing pneumonia (COP)
- Clinical
- Subacute onset of dyspnea, cough
- May follow an upper respiratory tract infection
- Systemic symptoms may also be present
- Average age mid 50's
- Majority of patients respond to steroids
- Subacute onset of dyspnea, cough
- High resolution computed tomography (HRCT)
- Patchy air space consolidation and nodules
- No honeycombing
- Histopathologic features
- Patchy involvement of lung
- Distal airways and adjacent alveoli filled by fibromyxoid plugs of granulation tissue
- All plugs appear to be at the same stage (temporal uniformity)
- Alveolar ducts and alveoli primarily involved
- Respiratory bronchioles usually involved
- Adjacent lung parenchyma is normal
- Mild to moderate interstitial infiltrate of plasma cells, lymphocytes
- Neutrophils and eosinophils infrequent
- Scant fibrin may be seen in air spaces
- Obstructive pneumonia may be seen distal to plugs
- Alveoli filled with lipid-laden foamy macrophages
- Minimal fibrosis
- No remodeling or honeycomb change
- Features not seen
- Hyaline membranes or abundant fibrin
- Granulomas or necrosis
- Prominent neutrophils or eosinophils
- COP/BOOP pattern may occur in the setting of acute exacerbation of a chronic interstitial lung disease such as UIP
- Underlying architectural changes such as peripheral honeycombing may help identify the diagnosis
- Clinical or radiographic history of pre-existing pulmonary disease is very helpful
Gerald J Berry MD
Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342
