Congenital lobar overinflation

Last revised by Mostafa Elfeky on 2 May 2022

Congenital lobar overinflation (CLO), previously called congenital lobar emphysema, is a congenital lung abnormality that results in progressive overinflation of one or more lobes of a neonate's lung. 

On imaging, it classically presents on chest radiographs as a hyperlucent lung segment with overinflation and contralateral mediastinal shift. 

Congenital lobar overinflation is more common in males (M: F = 3:1) 5.

Congenital lobar overinflation may be associated with an aberrant left pulmonary artery 7 and also with congenital heart defects:

Patients typically present with respiratory distress, most commonly in the neonatal period, and usually within the first six months of life 5.

In congenital lobar overinflation, a lobe (or more) becomes distended and may or may not have an overabundance of alveoli. There are many presumed mechanisms for progressive overdistension of a lobe, including obstruction, cartilage deficiency, dysplasia, and immaturity 2. Most cases are idiopathic.

Interestingly, there is a pronounced predilection for certain lobes:

Therefore, although the left upper lobe is most commonly affected, the right hemithorax is more commonly affected than the left 6.

The affected lobe tends to appear opaque and homogeneous because of fetal lung fluid or it may show a diffuse reticular pattern that represents distended lymphatic channels filled with fetal lung fluid.

  • appears as an area of hyperlucency in the lung with oligemia (i.e. paucity of vessels)
  • mass effect with mediastinal shift and hemidiaphragmatic depression
  • lateral decubitus film with the patient lying on the affected side will show little or no change in lung volume
  • lateral film may show posterior displacement of the heart

CT is usually performed to confirm the diagnosis, evaluate the mediastinal vascular structures, and to rule out other abnormalities. 

  • shows above features in greater detail
  • attenuation of vascular structures in affected lobe 4
  • may also show compressive atelectasis of adjacent lobes

Mildly symptomatic patients are usually followed up. Surgical resection or lobectomy is considered in severe cases 3.

General imaging differential considerations include:

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