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Congenital lobar overinflation

Congenital lobar overinflation (CLO) (previosuly called congenital lobar emphysema) is a congenital lung abnormality that results in progressive overinflation of one or more lobes of a neonate lung. Various methanisms have been postulated including an obstructive check valve mechanism at the bronchial level 2.

Epidemiology

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

Clinical presentation

Patients typically present with respiratory distress, most commonly in the neonatal period, and usually within the first 6 months of life 5

Pathophysiology

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

Associations

CLO may be associated with congenital heart defects such as:

Radiographic features

Interestingly there is quite a pronounced predilection for some lobes : 

  • left upper lobe: most common 40-45%
  • right middle lobe: 30%
  • right upper lobe: 20% 
  • may involve more than a single lobe in 5%
  • much rarer in the lower lobes.

Therefore despite the left upper lobe being most commonly affected, the right hemithorax is the most common side to be affected 6.

Plain film - chest radiograph
Immediate postpartum period 

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.

Later findings
  • appears as an area of hyperlucency in the lung with a paucity of vessels
  • mass effect with mediastinal shift and hemidiaphragmatic depression
  • decubitus films lying on the affected side will show little or no change in lung volume
  • lateral film may demonstrate posterior displacement of the heart
CT chest
  • shows above features in greater detail
  • attenuation of vascular structures in affected lobe 4
  • may also show compressive atelectasis of neighbouring lobes

Treatment

Mildly symptomatic patients are usually followed up. A lobectomy can be considered in severe cases 3

Differential diagnosis

Generlal imaging differential considerations include

See also

 

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