Tree-in-bud: Meaning in a Radiology Report

Also written as: tree-in-bud opacities, tree-in-bud pattern, tree-in-bud nodules

Tree-in-bud is a CT pattern of tiny branching spots in the lung, like a twig with buds. It usually means small airways are filled with mucus or pus.

What it means

The smallest airways in the lung, called bronchioles, are normally too thin to see on CT. When they fill with mucus, pus or fluid, or their walls swell, they show up as tiny dots joined by short branching lines. Radiologists say this looks like the tip of a tree branch covered in buds. It is a sign of a problem in the small airways, not a diagnosis by itself.

When it matters

Most often it points to an infection of the small airways (bronchiolitis) or to food, drink or stomach contents breathed into the lungs (aspiration). Less often it comes with tuberculosis or related germs, or with long-standing airway disease such as bronchiectasis. Many cases clear on their own or with treatment. If it persists, your doctor may suggest sputum tests or a follow-up CT.

Questions to ask your doctor

Does the pattern point more to an infection or to aspiration?
Is it in one area, or spread through both lungs?
If it does not clear, do I need sputum tests or a follow-up CT?

General information, not medical advice. What a finding means for you depends on your symptoms, your history and the images themselves, so talk your results through with a doctor.