Abstract / Summary
Hypersensitivity pneumonitis (HP) is an immune-mediated interstitial lung disease caused by inhalation of environmental antigens in susceptible individuals.Bird fancier's lung (BFL) is a well-recognised form of HP associated with exposure to avian proteins derived from feathers, serum, and droppings.Clinical presentation is variable and may range from relatively mild respiratory symptoms to severe hypoxaemia and respiratory failure.Early recognition is important because continued antigen exposure may result in persistent pulmonary inflammation and progression to chronic fibrotic lung disease.We report the case of a 27-year-old woman with no significant past medical history who presented with progressive dyspnoea over a one-month period, subsequently developing hypoxic respiratory failure requiring supplemental oxygen.She denied fever, chest pain, orthopnoea, productive cough, or peripheral oedema.She was a former smoker who had stopped smoking four years previously and had no relevant occupational exposures.Detailed environmental history identified prolonged indoor exposure to a rescued pigeon housed within the family kitchen.The patient required up to 10 L/min of supplemental oxygen.Computed tomography pulmonary angiography excluded pulmonary embolism but demonstrated diffuse bilateral ground-glass opacities with upper-lobe and perihilar predominance.Laboratory investigations demonstrated elevated lactate dehydrogenase and C-reactive protein, while renal function, liver function, complete blood count, and cardiac biomarkers were within normal limits.Extensive infectious and autoimmune investigations were negative.Serological testing demonstrated markedly elevated immunoglobulin G antibodies against pigeon serum, feathers, and droppings.The patient was treated with systemic corticosteroid therapy and strict avoidance of further avian antigen exposure.She subsequently demonstrated significant clinical improvement, with reduced oxygen requirements.The combination of a compatible exposure history, characteristic radiological findings, exclusion of important alternative diagnoses, positive avian-specific serology, and clinical response to treatment supported the diagnosis of acute hypersensitivity pneumonitis secondary to domestic pigeon exposure, consistent with bird fancier's lung.This case highlights the importance of detailed environmental history taking in patients presenting with unexplained dyspnoea, diffuse pulmonary infiltrates, and hypoxic respiratory failure.Identification and avoidance of a causative domestic avian exposure may provide an important and potentially reversible therapeutic intervention.