Tree-in-bud pattern

Last revised by Joshua Yap on 26 Mar 2024

Tree-in-bud pattern describes the CT appearance of multiple areas of centrilobular micronodules with a linear branching pattern, resembling a budding tree 11. Although initially described in patients with endobronchial tuberculosis, it is now recognized in a large number of conditions.

Simply put, the tree-in-bud pattern can be seen with two main sites of disease 3:

  • distal airways (more common)

  • distal pulmonary vasculature

More specifically, the pattern can manifest because of the following disease processes, often in combination:

While the tree-in-bud pattern usually represents an endobronchial spread of infection, given the proximity of small pulmonary arteries and small airways (sharing branching morphology in the bronchovascular bundle), a rarer cause of the tree-in-bud pattern is infiltration of the small pulmonary arteries/arterioles or axial interstitium 3,6,7.

Causes include:

The tree-in-bud pattern is not generally visible on plain radiographs 2. It is usually visible on standard CT, however, it is best seen on HRCT chest. Typically the centrilobular nodules are 2-4 mm in diameter and peripheral, within 5 mm of the pleural surface. The connection to opacified or thickened branching structures extends proximally (representing the dilated and opacified bronchioles or inflamed arterioles) 1-3,6.

ADVERTISEMENT: Supporters see fewer/no ads