Tree-in-bud sign
ChestHRCT
Centrilobular branching linear opacities with small nodular tips, resembling a budding tree, seen at the lung periphery.
What it means
Small-airway (bronchiolar) disease with impaction, most often infectious bronchiolitis.
Mechanism
Dilated centrilobular bronchioles fill with mucus, pus or fluid, making the normally invisible small airways and their branches visible.
Associated conditions
- Endobronchial spread of tuberculosis
- Non-tuberculous mycobacterial infection
- Viral or bacterial bronchiolitis
- Diffuse panbronchiolitis
Pearls
- A tree-in-bud pattern is almost always due to small-airway disease, usually infection.
- A rare tree-in-bud mimic from tumour emboli should be considered when infection is excluded.
References
- Radiopaedia: Tree-in-bud sign
For educational use only. This dictionary is a study aid and reference, not a diagnostic tool, and must not be used to guide clinical decisions or patient care. Imaging appearances vary; always correlate with the full clinical picture and confirm with a qualified radiologist.