Tree-in-bud sign

Saggital reformatted CT image showing "tree in bud" appearance of impacted distal small airways in Kartagener Syndrome.

In radiology, the tree-in-bud sign is a finding on computed tomography (CT) scans that indicates some degree of airway plugging.

It is associated with infection that has spread endobronchially and is classically associated with tuberculosis and bronchopneumonia. It is often seen in bronchiectasis, which may occur secondary to mucus plugging in cystic fibrosis.

The tree-in-bud pattern represents bronchiolar luminal impaction with mucus, pus, or fluid, which demarcates the normally invisible branching course of the peripheral airways. In addition, dilated and thickened walls of the peripheral airways and peribronchiolar inflammation can contribute to the visibility of affected bronchioles. In histopathologic studies, the tree-in-bud appearance correlates well with the presence of plugging of the small airways with mucus, pus, or fluid; dilated bronchioles; bronchiolar wall thickening; and peribronchiolar inflammation

References

• http://radiology.rsnajnls.org/cgi/reprint/222/3/771.pdf

External links

• Tree-in-bud schematic
• HRCT interpretation