Bird fancier's lung
ICD-10 J67.2 · ICD-11 CA70.2

Fibrotic Hypersensitivity Pneumonitis in Bird Fancier's Lung When Immunosuppressive Therapy Has Not Stabilised Lung Function

Clinical Scenario

This protocol addresses Bird fancier's lung presenting as hypersensitivity pneumonitis (HP) with established pulmonary fibrosis on HRCT — evidenced by reticulation, traction bronchiectasis, and/or honeycombing. The fibrotic phenotype carries distinct prognostic and treatment implications, and is classified separately from non-fibrotic HP in current international diagnostic guidelines.

Previous treatment — inadequate response

Immunosuppressive therapy — systemic corticosteroids combined with a steroid-sparing agent (mycophenolate mofetil, azathioprine, or methotrexate) — did not achieve the goals of disease stabilisation or slowing of progression, with ongoing decline in forced vital capacity (FVC) and diffusing capacity (DLCO).

Next-Line Approach

When fibrotic HP continues to behave progressively despite immunosuppression, current evidence supports a shift to an antifibrotic strategy targeting the progressive fibrotic disease behaviour. The specific agent selection, eligibility criteria, and management algorithm are detailed in the full protocol.

Treatment goal: Reducing the rate of decline in forced vital capacity (FVC) — disease stabilisation.
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References

DOI: 10.1111/resp.14847

Patients with HP may also display features of fibrosis, including reticulation, traction bronchiectasis and honeycombing (Figure 2B).

Recently published international diagnostic guidelines recommend HP classification into fibrotic or nonfibrotic phenotypes based on the presence or absence of radiological and/or histopathological fibrosis, supported by the observation that pulmonary fibrosis conveys important prognostic and treatment implications.

In such cases, there is good evidence for the introduction of antifibrotic therapy, as supported by the ATS/ERS/JRS/ALAT clinical guidelines for PPF.

Antifibrotic agent nintedanib is approved for HP patients with progressive fibrotic disease in Australia, but is not yet funded for indications other than IPF in New Zealand.

The INBUILD trial recruited patients with progressive fibrosing ILDs other than IPF (including fibrotic HP), demonstrating reduction in the rate of FVC decline in the nintedanib arm compared to placebo at 52 weeks, with a similar efficacy to IPF.

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