Panlobular emphysema is a morphological descriptive type of emphysema that is depicted by permanent destruction of the entire acinus distal to the respiratory bronchioles with no "obvious" associated fibrosis.
Panacinar emphysema is characterized by permanent destruction of the airspaces (alveoli) distal to the respiratory bronchioles. The pathogenesis relates to an intrinsic imbalance in the activity of protease/elastase released and an inhibitor of protease - alpha-1 antitrypsin.
Microscopically emphysema is depicted by abnormally enlarged alveoli with floating alveolar septa but as the disease progresses the lung parenchyma is further destroyed and intervening alveoli walls become harder to find. The term "panlobular" refers to the involvement of the entire acinus in contrast to the centrilobular distribution in a smoker. Macroscopically panlobular emphysema affects the lower lobes more severely.
Two distinct patterns have been described :
- localized form: multilobular distribution
- diffuse form: distribution not related to the zonal anatomy of the lung
Panlobular emphysema can either involve the entire lung in a rather homogeneous manner, or it may show lower lobe predominance .
- alpha-1 antitrypsin deficiency: classical cause and may show a lower zone predominance
- Ritalin lung
- Swyer-James syndrome: affects one lung
- obliterative bronchiolitis
- can also manifest as a normal senescent finding in non-smokers
The entire lung appears darker with attenuation of bronchovascular markings. The lung volumes are increased and distinct spaces of low attenuation may not be seen.
- Bronchiolitis obliterans