Chronic or cluster 2 hypersensitivity pneumonitis.Typical CT findings of biopsy-proven chronic hypersensitivity pneumonitis in a bird breeder. High-resolution CT scans show mild reticulation with superimposed patchy ground-glass opacities and traction bronchiectasis and bronchiolectasis (white arrowheads). Lobular areas of decreased attenuation and vascularity (black arrows) are also present.