congenital lobar overinflation

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.

Epidemiology

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

Clinical presentation

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

Pathology

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 . Most cases are idiopathic.

Associations

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

Radiographic features

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 .

Plain 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 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

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
  • may also show compressive atelectasis of adjacent lobes

Treatment and prognosis

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

Differential diagnosis

General imaging differential considerations include:

See also