Bird Fancier's Lung with Fibrotic Hypersensitivity Pneumonitis on HRCT: When Exposure Avoidance Has Not Improved Lung Function
Clinical Scenario
This protocol addresses bird fancier's lung in patients who have hypersensitivity pneumonitis (HP) with evidence of pulmonary fibrosis on HRCT — specifically reticulation, traction bronchiectasis, or honeycombing. The presence of these fibrotic features classifies the disease as fibrotic HP, a phenotype that carries distinct prognostic and treatment implications.
Prior Step — Exposure Avoidance Did Not Achieve Its Goal
The preceding step focused on complete removal of causative exposures: eliminating birds, feathers, and droppings, and thoroughly deep cleaning soft furnishings. The target was improvement in lung function following removal of those exposures. When lung function does not improve after this step, further management becomes necessary.
Next-Step Approach (Partial Overview)
When both inflammatory and fibrotic features are present, immunosuppressive therapy may be considered as the next step. The approach involves a combination strategy — the full protocol specifies the relevant agents, criteria for their use, and the clinical rationale that applies in this fibrotic setting.
Clinical goal: disease stabilisation or slowing of progression, with maintenance of lung function (FVC, DLCO).
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.
- Despite this uncertainty, when both inflammatory and fibrotic clinical features are present, immunosuppressive therapy may still be reasonable, albeit with a lower expected magnitude of benefit than predominantly inflammatory lung disease.
- In some patients, upfront combination low-to-moderate dose corticosteroids and steroid-sparing therapy may be reasonable, particularly if unacceptable risk of steroid side effects prohibits higher dosing.
- For nonfibrotic HP, improvement in clinical parameters with therapy may be expected, whereas disease stabilization (or slowing of progression) may be more realistic goals in patients with predominantly fibrotic HP.
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