| ABPA |
- Requires structural airway disease (asthma or CF) as prerequisite
- Total IgE typically >1000 IU/mL
- Peripheral eosinophilia
- Fleeting pulmonary infiltrates + central bronchiectasis on CT
- Aspergillus-specific IgE / positive skin prick test
- Treated with systemic glucocorticoids + voriconazole
- Non-resolving pneumonia despite adequate antibiotics
|
| Hypersensitivity Pneumonitis |
- Exposure to organic antigens (bird droppings, moldy hay, hot tubs)
- Restrictive pattern on PFTs
- No significant IgE elevation
- Bilateral ground-glass opacities (acute) or fibrosis (chronic)
- Improves with antigen removal
- Precipitating IgG (not IgE) antibodies to offending antigen
|
| Granulomatosis with Polyangiitis |
- c-ANCA (anti-PR3) positive
- Upper + lower respiratory tract + renal involvement (triad)
- Necrotizing granulomatous inflammation on biopsy
- Saddle-nose deformity (septal perforation)
- Treated with rituximab or cyclophosphamide + glucocorticoids
- Not associated with IgE elevation or eosinophilia
|
| Strongyloidiasis |
- Endemic to rural tropics / Southeast Asia
- Larvae penetrate skin → pulmonary phase (Löffler syndrome) → GI invasion
- Larva currens: serpiginous urticarial rash tracking rapidly across skin
- Eosinophilia + elevated IgE present
- Treated with ivermectin
|