The changes are characteristic of pulmonary fibrosis.
This patient had a long history of exposure to pigeons as a hobby, and the CT findings are in keeping with end-stage chronic hypersensitivity pneumonitis.
On HRCT, chronic hypersensitivity pneumonitis usually has the following features:
- established pulmonary fibrosis with honeycomb formation
- may see ground glass opacification
- areas of lobular air-trapping