Congenital malformations
_Cystic adenomatoid malformations
Maturation arrest in lung segments
_
_Azyous lobe
Superior apical bronchus grows medially instead of laterally; vein is at bottom of superior lobe fissure
_Sequestration –
Accessory piece of lung that becomes disconnected from tracheobronchial tree and parasitizes systemic circulation from diaphragm.