Tree-in-bud sign
| Tree-in-bud sign | |
|---|---|
 | |
| Sagittal reformatted CT image showing "tree in bud" appearance of impacted distal small airways in primary ciliary dyskinesia | |
| Differential diagnosis | airway obstruction |
In
mycobacterium avium intracellulare, bronchopneumonia, chronic aspiration pneumonia, cystic fibrosis or cellular impaction from bronchovascular spread of malignancy, as can occur with breast cancer, leukemia or lymphoma.[2] It also includes lung manifestations of autoimmune diseases such as Sjögren syndrome or rheumatoid arthritis.[3][4]
Histopathologic studies have shown that the tree-in-bud pattern is caused by demarcation of the normally invisible branching course of the peripheral airways, which usually results from bronchioles being plugged or blocked with mucus, pus or fluid. In addition, dilated and thickened walls of the peripheral airways and peribronchitis can make the affected bronchioles more easily visible, as is seen in patients with cystic fibrosis.[citation needed]