Extrinsic Allergic Alveolitis

Extrinsic Allergic Alveolitis

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


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