Pigeon Fanciers Lung: Hypersensitivity pneumonitis in domestic bird carers


Caterina M. Klasen, Evelyn C.R. Wilkins, Claudia Suttie, Isabella Suttie,
Dr Daniel T. Tardo

Abstract

Pigeon fancier’s lung is a leading cause of hypersensitivity pneumonitis which remains under-diagnosed worldwide. It is an IgE mediated lung disease which occurs when a susceptible individual is repeatedly exposed to airborne avian antigens often found in the excrement and feathers of birds. While it is an uncommon condition, hypersensitivity pneumonitis is a key differential in those presenting with chronic or severe dyspnoea, and those working in close contact with birds. Interestingly, not all individuals who are exposed to environmental triggers develop a hypersensitivity reaction. This is postulated to involve genetic factors and a two-hit model of pathogenesis, much like many immune mediated reactions. Diagnosis is supported with a thorough history and confirmed through specific avian and pigeon antibodies, eosinophilia and exclusion of other common causes of breathlessness. 

We present the case of a 19 year old female with a week long history of dyspnoea on a background of severe asthma. Her symptoms were not relieved by salbutamol and were accompanied by a productive cough and wheeze. Collateral history revealed that she cared for a pigeon for some months prior to her presentation. On examination, the patient was found to be in respiratory distress. She was sedated, intubated and commenced on piperacillin-tazobactam, azithromycin and hydrocortisone. Her chest CT revealed ground glass appearance in all lobes and early airspace opacity in the right hilum. Haematological studies revealed raised eosinophils and neutrophils. Avian, budgerigar and Pigeon antibodies are currently in progress. Predominant cytology of bronchial washing specimens showed eosinophils, lymphocytes and Charcot-leyden crystals consistent with eosinophilic disease process. Her condition improved with the administration of glucocorticoids. 

This case demonstrates a typical clinical presentation of eosinophilic hypersensitivity pneumonitis, an important cause of dyspnoea in the context of specific environmental exposures.