Viral bronchiolitis (plural: bronchiolitides) refers to a bronchiolitis secondary to viral etiology.
Pathology
Viral bronchiolitis is due to viral infection of airways which results in inflammation and peribronchial edema. This can then result in occlusion of the small airways leading to hyperinflation and subsegmental atelectasis. Children are more susceptible due to their smaller airways.
Etiology
Common causative viruses include:
- respiratory syncytial virus (RSV): 60-70%
- human metapneumovirus (hMPV): 5-15%
- adenovirus types 3, 7, 21
- rhinovirus
- parainfluenza virus
Radiographic features
Plain radiograph / CT
May show
- hyperinflation
- increased (commonly bilateral symmetrical) peribronchial thickening and lack of focal lung consolidative change
- segmental/subsegmental/band atelectatic changes
- small lobular air trapping
- increased AP diameter may be seen