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