Pathology: Hypersensitivity reaction toinhaled allergens
Acute phase: inflammation
Chronic exposure: granuloma formation, bronchiolitis obliterans
Aetiology: Multiple allergens: bird fanciers lung,pigeon fanciers lung, farmers lung (Micropolyspora Faeni), malt workers lung (Aspergillusclavatus)
Symptoms: Acute (4-6hrs post-exposure): drycough, dyspnoea, fever, rigors, myalgia.
Chronic: progressive dyspnoea, weight loss, corpulmonale
Signs: Crackles,fever, weight loss if chronic process.
Investigations: FBC: ↑WCC (neutrophils), ↑CRP/ESR
Chest X-Ray: bilateral mid-zone shadowing
Spirometry: restrictive defect, allergen testing
Treatment: Removeoffending allergen, in the acute phase give oxygen if hypoxic and steroids
Complications: Mayprogress to permanent lung damage if chronic exposure, type 1 respiratoryfailure, cor-pulmonale
Prognosis: Resolvesif allergen removed +/- steroids in the acute period
