Hypersensitivity Pneumonitis (HP)
Hypersensitivity pneumonitis (HP) is a form of interstitial lung disease caused by an immune reaction to inhaled organic dusts or chemicals — common triggers include bird droppings and feathers, mould, and certain occupational exposures. Dr Mackintosh assesses and manages HP for patients across Brisbane and Queensland.
Diagnosis
A detailed exposure history is central to diagnosis — occupational exposures, the home environment, and hobbies such as bird keeping are all relevant. See HP Lung for a comprehensive list of potential exposures. HRCT typically shows a mosaic pattern with air trapping, with or without fibrosis in chronic HP, and bronchoalveolar lavage may show a lymphocytosis. Multidisciplinary team discussion helps distinguish fibrotic HP from other fibrotic ILDs, including IPF.
Management
Identifying and avoiding the causative antigen is the cornerstone of treatment. Immunosuppression may be used for inflammatory, non-fibrotic HP, while antifibrotic therapy may have a role where fibrotic HP is progressive (see progressive pulmonary fibrosis).
Patient information
- Hypersensitivity Pneumonitis (HP) — fact sheet, Lung Foundation Australia.
- What Is Hypersensitivity Pneumonitis? — patient education series, American Thoracic Society.
Frequently asked questions
What causes hypersensitivity pneumonitis?
HP is caused by an immune reaction to a repeatedly inhaled antigen, commonly bird droppings or feathers, mould in damp buildings, or certain occupational exposures. In many patients no specific trigger is ever identified.
Can hypersensitivity pneumonitis be cured by avoiding the trigger?
Identifying and avoiding the trigger is the cornerstone of treatment and can halt progression, particularly in earlier, non-fibrotic disease. Once significant fibrosis has developed, avoidance alone may not reverse existing lung damage.
How is HP different from IPF?
Both can cause lung fibrosis, but HP is triggered by an identifiable or presumed inhaled antigen and often shows different HRCT and pathological features. Distinguishing fibrotic HP from IPF matters because management, including antigen avoidance, differs.
For referring clinicians
Referrals are welcome for patients with suspected hypersensitivity pneumonitis, including where exposure history is unclear or HRCT findings are ambiguous.
Related
Interstitial lung disease — HP is one of several ILD subtypes Dr Mackintosh assesses and manages.