- Eosinophilic pneumonias (pulmonary eosinophilia) represent a heterogenous group of diseases with a similar clinical syndrome and overlapping findings on imaging.
- Primary and secondary causes (1,2,3):
- Acute idiopathic eosinophilic pneumonia (AEP)
- Chronic idiopathic eosinophilic pneumonia (CEP)
- Eosinophilic granulomatosis with polyangiitis (EGPA) previously called Churg-Strauss syndrome (CSS) (4)
- Simple pulmonary eosinophilia (SPE, i.e., Löffler syndrome) also overlaps pulmonary infiltrates with eosinophilia syndrome.
- Hypereosinophilic syndromes (HES)
- Eosinophilic bronchitis
- Secondary causes: allergic bronchopulmonary aspergillosis (ABPA), parasitic infections, drug or toxin induced
- Uncommon in United States, rates not specifically reported
- CEP ~1–2% of all interstitial lung disease (ILD)
Etiology and Pathophysiology
- No single etiology for the diverse cluster of diseases
- Idiopathic (AEP, CEP)
- Hypersensitivity (ABPA, Löffler syndrome)
- Cigarette smoking (AEP)
- Heavy dust and other occupational exposures (AEP)
- Infectious: parasites, filariae, nematodes (Löffler syndrome), specifically Ascaris most common worldwide. Others include Strongyloides hookworms, filarial nematodes, Toxocara, and Paragonimus.
- Drug induced: 120 known associations; most common: NSAIDs, minocycline, nitrofurantoin, cocaine
No known genetic pattern
Commonly Associated Conditions
- Asthma (ABPA, EGPA)
- Cystic fibrosis (ABPA)
- Atopy (notable for CEP)
- Tobacco use (AEP)
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